Trans Inf is one of those squads that just doesn't fit into PR. With the recent talks about how a team in PR should work together as a team, this seems like one of the things that should be given some thought. IMO this should be an official rule.
TL;DR:
Mech Inf (2 APC crew + 6 inf) is a plausible combo squad for which we established a rule. On the other hand, Trans Helos/Tanks/AntiAir should be available to support the entire team. Having a private pilot for your squad is like playing Vanilla BF2 where nobody cared about another squad's needs.
Reasons to not allow Trans Infantry, Anti-Air infantry, etc:
1) Non-optimal functioning of an asset due to private piloting or disregarding other SL's requests.
2) Assets remain unused after respawn because the pilot decides to do field infantry work after dying.
3) Tensions between legitimate Trans/ Tank/... squads and Trans Inf/ Armor Inf because both claim to have the right to a vehicle.
4) 'Squad Mingling' leads to more Vanilla-like playstyle with less desire for teamwork.
5) Great tendency to park air assets near capzones, going inf and switching back to pilot kit. This brings a huge risk of losing the asset.
Opinions greatly appreciated, as always ;).