After discussion in IRC, it seems we're likely going to run with 4 classes in EGS. Namely, Hunter, Ranger, Force and Acrotecher(?).
The classes themselves would start off with basic access to weapons and will be able to select customisations as they level up, using class level as the limiter as to what they can access.
For example, at class level 10 you may unlock access to B rank weapons appropriate for your class, level 20 B rank weapons less so (a hunter could unlock guns or techer weapons - this is how hybridisation is handled under this system it's entirely up to the player themselves). Both might set you back 5 of your 20 points however (or go with PSP2's system where inappropriate weapon types cost more). All classes would eventually be able to use Srank weapons of various types, as well as raising their PA caps and other things. The class type cap would be 99 or something around that.
So why two techer types? Especially a hybrid one? Well I'd argue it's necessary due to group expectations. If someone is coming as a Force and AT didnt exist you may feel wronged if they don't bring buffs or improved heals. Remember the whole Forces = Nurses thing? This allows Force to sit with the other offensive types on relatively equal grounds without having to worry about being shunned from parties because they didnt want to play support. Until a better solution is proposed, I see Acrotecher as necessary because of this.