So...every battle in SAV is gonna be like FE, huh? Replace the Rail Gun with a Power Dragon and you're set to win pretty much no matter what the enemy matchup is. No hiding, no flying; only Force Field is a 'defense' but that's not enough. Players of course will love it because it makes things easy, but I really question the balancing here.
I don't know that it's a balance problem exactly.
It does seem likely to be quite vanilla - where basically none of the abilities of the units really matter because they're neutralized by most other units. You're focused on power shot, but terrain and unit bonuses at high boost aren't that big a deal anyways (equivalent to at most 30% extra boost where relevant).
But given that SAAB has been pretty much torture with 1 army to which there is no way to outplay at high boost (8 nail storms), I'll take no army being a challenge as an upgrade
The fast unit's flying only affects its movement because the artillery has power shot.
The light unit's hiding only affects other light units and heavy units because the fast unit will kill it before it can hide, and the ranged and artillery can see through stealth.
The ranged/artillery units abilities pretty much just negate the things they couldn't otherwise hit because of their abilities.
The heavy unit is just bad. Reactive Armor 4 isn't enough to be too durable in a world of AO crit + Keen Eye procs. And the artillery shoots through it anyways.
At medium attrition you likely will be able to load in anything other than heavies with an appropriate mix of rogues against any target... Fasts can hit first. Artillery and Ranged can hit anything, and you can combine with rogues to absorb first hits.
At high attrition the light unit stands out as the one that might be able to go the longest due it having the highest base attack - but as one of the only units that actually has limits on its ability to hit things it'll have to pick specific armies to go against. It would be in best shape combined with rogues against armies that feature a lot of fasts that charge into range to turn rogues and then die.
You'll probably try to make fasts or artilleries work as long as possible for the ease with which they can hit things - but as their stats are slanted more defensively they'll see their performance drop off faster at high attrition unless your boost is significantly more oriented to defense than offense.
With no effective defensive abilities AO will be key to maintain regular enough 2-shots at high attrition and surrender and re-enter when you don't get the rolls you want.