[Neurotoxin]

Yeah, I'd imagine CR5 should take a few months to attain, even from CR4. Games like EVE show that its okay to make badass stuff take years to be able to use.

During the demo, Squad Leading tree was on every class, but I couldn't tell if the unlocks are shared across every class or if CR5 has to be unlocked for every class separately.

Also, in terms of the labels on the weapons used by each class...
Heavy Assault used "LMG"
Engineers and Light Assault used "Carbine"
Medics used "Assault Rifle"
Infiltrators used "Sniper Rifle"

While this was just a demo, I think that is shows one promising possibility - little primary weapon restriction from one class to another. I could imagine that there is a significant worry that the class system will do like many other games, and limit the arsenal of the character based on their class. Considering snipers used to be 3x9 and completely unable to be carried by infiltrators, and now it is one of the weapons they were featured with, I have to imagine that EVERY class will be able to use Snipers and Shotguns and Rifles / Machineguns of all varieties, aside from class tools like the heavy weapon on HA.