(Not a story about a move from exclusive to non-exclusive, but some thoughts related to this).
At this point in the evolution of royalty free markets, most are very crowded and competitive. Others are less saturated, but not visited that much. That said, some of these markets sometimes attracts different buyers. Even things as superficial as a different website design have the potential to appeal to a different client base, so I think it’s a good idea to try a few and see what you can make after a few months (or years… sometimes, it’s slow to kick in!).
A zero sale item here could turn out to be a steady seller at another place or vice-verse.
Of course, other markets are not entirely different. You will still find tons of corporate/happy/epic/etc, but some buyers simply have their habits and like to buy at specific sites. Having things at a few places can help even out sales.
(But then, don’t forget to factor in the hassle of loging to many sites, dealing with different uploading interfaces, specific keywording/descriptions structures, different rules, etc. Nothing that can’t be learned in a few days, but it’s a bit more work than doing it all on a same platform).
Ps: I’m just a small (80 percent sfx / 20 percent music) business, so it could be different for a 100% musical venture, but probably similar, I guess.
I chose to be exclusive here and try to mostly upload sounds/logos that fit this market client’s base, but I spread other eggs at other places. Didn’t found many gold mines, though. (Hope I wasn’t too off-topic. Just thought that another opinion about selling at different platforms could maybe help your reflexion a bit somehow).
Good luck with this move. Please keep us updated.