excuse me, but I don't think this is a good idea. My opinion is that in the future all microstock agencies will have exclusive contributors because these are their real future (one of my images, for example - I'm an exclusive in dreamstime - can be purchased only here and NOT in other agencies), so exclusive contributors will have a better treatment in the next years.
This future has already begun (I think it's started a sort of "big war" between all agencies), so it's not a good idea stop to be an exclusive at this point. I don't stop to be exclusive: please, think about it.
I suggest you to continue to be exclusive, but also to find other ways to sell Your creations, for example searching direct buyers or similar.
Good luck, I stopped being exclusive for two months because I had some spare time, and my sales dropped to 1/3 of what I normally getting. I started working in othe sites, but didn't see any sales in two months, of all the sudden my spare ended and I decided to cancel in other sites and apply again to be in exclusive here.
- Nikkor 70-300 mm - Nikkor 18-105 mm...
I think at some stage every photographer or designer who is exclusive considers this matter - about a year ago I went through the same process with the result to stay - and do more for my portfolio - and see - now I'm glad I did both - stay and do more :)
Nikon D700 with Nikkor's, Nikon 90x, Leica X2, Canon S100