Unless RF stock is the only gig (or the main gig) you've got going, I would argue that being exclusive is definetly worth your while.
I have already gone over my reasons for my Exclusive Decision in another blog post, so I am not going to repeat those points.
One thing that I didn't take into account is that I am doing ALOT less uploading and tracking and categorizing than before, and I have not lost very much income by not uploading to other sites. Prior to becoming exclusive here, I uploaded to 7 sites. Only two other sites made me any money worth mentioning, but I have made back the income from one site with the additional 10% income from exclusive sales. The $0.20/image that I made when I went exclusive is more than I would have made in a YEAR at the second site, so I would say that, for now, I have broken even, at the very least.
Besides making more money, though, I have more time to actually get out there and SHOOT! More time to make images means more stock to upload.
Bottom line is that I put less time in and make just as much money, which is more true to what I became active in stock for to begin with. Residual income!