Magrider and Prowler Armor Specs are identical: http://www.ps2calc.com/#vehicle1=Magskater&vehicle1Upgrade2=1&weapon1=Vanguard HEAT http://www.ps2calc.com/#vehicle1=Prowler&vehicle1Upgrade2=1&weapon1=Vanguard HEAT
The issue with the TR SMG is that the SMG's offered bonuses double-dip on the TR faction bonuses. TR carbines have a larger magazine - that is the TR faction bonus. The SMG has a larger magazine, that is its bonus. There's a conflict of interest here, and that's the main problem. "Hey, I'm a carbine. My bonus to my faction is extra ammo per magazine." "Hey, I'm a SMG. I can also be used by the carbine classes. My bonus is that if you spend 100 certs and an underbarrel attachment slot on me, you can have as much ammo as your carbine." We're in the ol' Mac vs PC commercials here. The TR smg's offer something that's already offered already as a faction specialty. Vice versa, take the NC SMG, tack on the extended magazine, you have 35 rounds instead of 30, and higher damage per magazine than say the GD-7F (and in a game where you need to consider the most efficient way to dispatch two or three enemies who are attacking you, and not just 1v1, damage per magazine can rival damage per second in usefulness). For NC, the SMG can actually be considered as providing some sort of use. That is not to push the point that one SMG is statistically better than another SMG *cough vanu COF cough*, but it doesn't offer a practical use for, say, light assaults or engineers on TR.
The SMG reload speed bonus overlaps with the Vanu reload speed bonus, too, so there's that. Honestly, the TR, NC, and VS SMGs all have things their Empire-respective carbines don't. The VS Eridani and NC Cyclone get more ammo than any carbine while doing similar damage per bullet to their respective carbines, and the TR Armistice has a higher fire rate than any TR carbine (the highest firing rate in the game right now, actually, and some of the weakest bullets to boot). All also have faster tactical reloads than the vast majority of carbines of any Empire, and faster ADS speeds than most weapons for all Empires (Vanu have fast LMGs, NC have more fast ARs, TR have fast carbines). They are all also a lot cruddier general-purpose weapons for LAs and Engis than their top tier CQC carbines (Lynx, VX6-7, and GD-7F), with super slow projectile speeds (worse than most Vanu guns even) and ridiculously steep damage drop off, and what feels like pretty bad COF at range. So yeah, the whole "SMGs are impractical for most classes" is true of all 3 Empire SMGs, not just the TR.
