If you're going to look to other's stats, I think it's important to not really compare yourself to photographers, but only to vector artists. The sites seem to have a very different market share for that market.
As far as exclusivity in general, I suggest not keeping 100% of your income from 1 site on a long-term basis. Looks like you're doing that with other jobs. And I think you're right to primarily use your own stats as the basis for your decision. Good luck!
Agreed.
Try excl out for a few months. But realize that being exclusive is like digging a hole. The longer you stay, the harder it is to get out.
I have no doubt you will make more $$$ than you are currently, considering your figures, unless best match kills your top file which should be a huge concern. Good luck!