Good proposal overall. I'm all for balancing AT and suppression options between USF tiers.
Why does LT have both AAHT and HMG, while Cpt have access to zook (without racks) and AT gun?
As much as I understand the thought process behind such design the idea is that:
1. There must be a reason to back tech
2. You are supposed to supplement lacks of your army composition with commanders
3. You can choose the tier that counters opponents strategy
Somebody can say that this narrows the number of commanders that are worth using. But then you can look at axis factions, which both have counters to every possible threat in their early tiers and still use same commanders over and over again.