Classes like these will not be a good idea. Yes spawning with 25 HP and a weak-ass weapon, with faster speed seems fair enough. but it's not.
As soon as you spawn, you can drop that weak-ass scout and get an M4/AK (Or weapon of choice) easily. Most maps even have Medic and Armor stations. Basically you are just making a class that will give anybody a free 1.5 speed/gravity boost.
I also doubt you can limit health / armor to x for my own reasons (Waaaay to TL;DR and confusing, but i know)
EDIT: Same goes with any class that have major benefits like health, armor, gravity, speed increase. Most i like are just weapon changes, so we don't have to spend 20 seconds to grab guns and leave armory.