Uh, yes it is, when you are in the middle of a hunt and you have to stop, maybe even mid mob, to repair your amp it is a HUGE deal.
Also, as Xanato stated, portable repair is an added expense. Try using an Arkadia shortblade for a month to hunt and you will see just how annoying it is when you have to repair your blade every 18-22 minutes. that extra armor decay eats ped as you are repairing in the middle of being attacked. Also, the smaller TT means you have to sit there and watch your amp decay to avoid repairing mid mob.
They are basically the same amp in terms of dmg and dpp (slight difference).
I have asked this same question of a bunch of people and always come back with the same answer...Max TT.
Imp A105 also has a higher share of its cost incurred per shot in the form of Ammo usage as opposed to item decay which is advantageous because it allows you to burn more UA/Shrapnel than the A106.