Here's some interesting stats from the CCT beta...
Of over a thousand characters created during the beta,
42% were females,
40% were males,
18% were 'big guys'.
Of those,
28% were tanks,
25% were brawlers,
31% were devastators,
16% were support.
That all looks pretty good from a distribution viewpoint. If this is maintained at launch, all roles will be nicely supported and there should be no problems creating well rounded teams :)