I don't have alot of (any?) guys who use prepaids so I can't really speak to personal experience with that. Overall the decline rate is slightly higher than with other options like ccbill but not by much. My biggest issue is that my regs who use proxies tend to get declined. It's annoying but that's partially why I use it in conjunction with other options
in terms of downtime, funnily enough my zombaio was actually offline one day last week. That was a first for me, though. I use it pretty heavily and I've never experienced that issue until that day, although if it did become a trend I'd obviously reconsider using it.
funny, when I first saw your sig I hated you for a moment, based on the title I thought for a sec that you were starting up a site warehousing pirated cam shows
Your actual concept is pretty prescient, though. A lot of chicas are tired of adult-unfriendly file storage sites and are looking for new options for sending download links, so your site could def address a need. Good luck with it