There's no absolute requirement for each model to be assembled with equipment according to their roster entry, particularly as upgrades will be acquired throughout the course of a campaign. So far we've mostly tended to stick with whatever equipment the models have, but that's really just been for ease of getting to grips with the game . As long as you've got a clear record of what each model is carrying (and don't mind being repeatedly asked for reminders from those with the short-term memory of a goldfish i.e. me) then there shouldn't be a problem.
Figures painted in 2016: 4
"What this game needs is a panda with a chaingun."
"What this game needs is a panda with a chaingun."