I've been with BNPS Worldwide for a short time, but in that time I have already seen them update their web site (in the last month) and add a really nice referral program (where there was none before). My portfolio is very small there and I have been slowly adding to it, but the photographer who referred me there tells me he's been there for a while and done really well. A lot of sales at different times during the year when magazine companies purchase large amounts of photos for their upcoming issues.
Their upgrade also increased the file sizes they accept including the total size of the five photos. Before it was quite small and some of my batches could only be uploaded three at a time instead of five to meet their size limits. The one thing I wish they would do is include more reasons for a reject, sometimes no reason at all for a rejected photo.
I'll also add my referral link (10%) to sign up there:
BNPS Worldwide
Custcaster does look pretty nice. I hope they take off and I'll have to watch to see what happens with them.