Please, please don't reduce equipment count on any logi. 2 at standard is NOT ok, it is the same as what scouts have, how is the logi supposed to be the equipment specialist if a std scout can do the same job as a std logi? 3/3/4 as the Min has at the moment is acceptable, though I think you will find a lot of logis would support a 3/4/4 progression (if not 4/4/4), for good reasons too. The equipment is what defines the logistics class, making the 4 unlock only at proto is inelegant in my opinion (though, I assume some would say 4 at even adv is somehow OP :/). And giving logi suits only 2 equipment slots at std is worse. And yes, that is what the Cal and the Amarr have at the moment, there are reasons why so many of us logis have been asking for this slot progression balance pass for a long time ;)

Personally I believe that the Caldari extra (low) slot in trade for the one equipment slot is fair, but unnecessary... It should really just have the same standard slot progression, just mirrored with the Gal, but I thing actual Cal logis should weigh in on that. With one less low slot but another equipment, it would still need some adjustment to its CPU (as you are correct, it is paying for the old sins of it's original suit bonus and the power of the tac AR).

The Amarr logi trading a sidearm for an equipment is also fair enough, it should get the same amount of total slots as the others as well.

what if proto is "only" 7 high/lows

As in only logos can equip them, or that logos can't equip rifles? Personally I feel like that's removing sandbox play, but its definitely a workable compromise with some tweaking.

EDIT: Or how about (if possible) Cal deployables got some sort of extra flux resistance?.