I want to come up with another 1st tier perk, I've put an extra perk in the 2nd and 3rd perk tiers, as I will list below. But I feel like there's probably something we could stick in the 1st tier slot.
Anywho here's what I would do.
Regular - Invisible to thermal and killstreaks. (pretty cut and dry)
Pro - Faster lock-on with launchers and (tentatively) more damage to enemy air support with bullets.
Now I'm taking thermal invisibility away from Assassin and giving it to Blind Eye, because it makes more sense to me. Also I would make the faster launcher lock-on effect work on ground targets, meaning Stinger vs. Assault Drone/Juggernaut would be quicker, as would Javelin locks on ground positions. Although I might take the more damage vs. enemy air support and give it to that additional 1st tier perk.
Regular - Pick up ammo for primary and secondary weapons (non-launcher) from drop bags.
Pro - Start with more ammo for primary and secondary weapons (non-launcher).
I'm not changing this, I know a lot of people want Scavenger to resupply grenades, but there's a very good reason not to do that. Scavenger + Recon with Specialist would become an absurdly powerful combo, and make Specialist dudes nearly unstoppable. Plus grenade spam is annoying in the first place.
Regular - Explosive damage paints enemies on the HUD for 6 seconds.
Pro - Bullet damage paints enemies on the on the HUD for 6 seconds.
Not changing the duration or anything else. However, while marked enemies should lose the stealth effects of Blind Eye and Assassin. Meaning they'll be detected by killstreaks and/or UAV. Also Stalker users shouldn't get the delay effect while marked either.
Regular - Increased Sprint (x3)
Pro - Faster mounting and climbing. Doubled sprint recovery.
Unlimited sprint can be pretty abusive, especially in objective game types. So I've decided that the triple sprint capacity is where it should be. The Pro effect will increase mounting speed, as well as climbing speed for ladders. I've also added an effect to the Pro version which doubles sprint recovery, meaning you can more effectively use your sprint. This will give someone with Extreme Conditioning the ability to catch someone without it, which is lacking otherwise.
Sleight of Hand
Regular - Faster reloads.
Pro - Faster weapon switch.
This one I'm also unsure of, while I am perfectly ok with how it works in MW3. I have thought about making Quickdraw Pro more of a Scout Pro effect, although that seems to weaken Sleight of Hand quite a great deal. So if anyone has any ideas on how to split the Scout Pro effects between SoH and QD, let me know.
Regular - Faster ADS
Pro - Faster grenade and equipment use.
Basically no real changes, although I would reduce the ADS effect on sniper rifles, to more or less debuff Faze/Optic douche-faggery. I loved the way sniping felt in Black Ops, sorry if you don't share the feeling. Also, I think the Pro effect should effect calling in killstreaks as well as grenades and equipment, as Scout Pro did in Black Ops.
Regular - Invisible to UAV, Portable Radar, and HBS.
Pro - No red name when targeted.
No more immunity to CUAV or EMP. I have thought about giving Assassin a reduction effect vs. Recon instead of Dead Silence, but I'm not sure. I don't think Assassin will have a lack of use if the above were it's effects, so I feel it's still plenty strong.
Regular - Reduced explosives damage.
Pro - Reduced flash/stun effects.
I'm not changing what it does, but I would improve it's effect vs. tactical grenades. That effect should be more akin to Tactical Mask Pro in Black Ops, giving you relative immunity from highly annoying flash spam.
Regular - Killstreaks/pointstreaks take 1 less kill/point.
Pro - 2 assists equal 1 kill/point.
Nothing to change, Hardline is one of the more balanced perks in MW3, in my opinion.
Regular - Pick 2 primary weapons.
Pro - Movement speed based on the faster of your two weapons.
I'd basically make class mobility dependent on your starting primary, so no more being slowed down by picking up weapons. And making Overkill more or less what it was in CoD4, a pseudo-lightweight for slower weapons. I would probably also add a slight speed reduction if you are using Overkill with a Riot Shield to prevent abuse, but honestly the shield is complete shit. Anywho, you get the idea.
Juggernaut (don't flip out just yet)
Regular - Reduced flinch.
Pro - Faster health recovery.
So this version of Juggernaut doesn't make you able to absorb more damage. It removed Focus as a proficiency, which I guess could effect some things, but it's a very strong proficiency and I think it's better suited as a perk. And faster health recovery is a pretty cool effect as well, if you ask me. It could have some interesting uses, plus it's also ****ing annoying how long it takes health to recovery in MW3.
Regular - Longer breath hold.
Pro - ID enemies at longer ranges.
I've swapped the effect around so you have to get the Pro version to get the abusive effect. I would also tone it down some, and try to remove it's wall-hack tendencies.
Regular - No movement penalty while ADS.
Pro - Delays enemy detection based explosives.
I wouldn't really change anything. But, there's one thing I'd like to do. When using Stalker, you don't slow down while going ADS vs. walking; but you also don't get any quieter. If anyone has suggestions on what to do with Stalker, I'm glad to hear them out; but despite it's cheesy nature at times, I like the perk; it forces variety in the 3rd tier slot. I might also give it's Pro effect to Hacker, which is part of my splitting up of SitRep's effects.
Regular - Enemy equipment appears in red.
Pro - Hack enemy equipment and booby trap care packages.
Basically bringing hacker back. I might take Stalker Pro's effect and add it to this, as Hacker isn't directly offensive or effecting the enemy it could use some powerful effects. I would also consider giving it the ability to increase the speed at which enemy care packages can be picked up. Also some of these effects could be swapped around with that 1st tier perk I'm looking for.
Regular - Enemy footsteps are louder.
Pro - Friendly footsteps are muffled.
Basically SitRep Pro, fully able to counter Dead Silence, as a stand alone perk. Eavesdrop was a really stupid perk in CoD4, but I like this idea. I'm not sure about muffling friendly footsteps all that much, but whatever, this is the idea. I am also totally ok with making the effect vs. Dead Silence as though neither perk was in play, not totally ignoring it and making DS users as loud as everyone else.
Regular - Improved hipfire accuracy.
Pro - No ADS delay from sprinting.
The same, it's a good perk.
Regular - Makes footsteps silent.
Pro - No falling damage.
So there's what I'd do.
Let me know if you have any comments on my changes, and more importantly, have any ideas for another 1st tier perk.