What kind of events are you looking at?
The lack of hills is nice, so there isnt the same concern as road cycling
But weight is still a concern if you plan to compete, extra weight still has to be moved around. I think Ive read that 10lbs is .5 seconds off a kilo. Probably more significant in a pursuit.
Bigger is usually less aero too, although Im not sure if 5-10lbs would make change that much.