I've no idea how their novel-length works sell.
Their anthologies do pretty well, though there's a lot of variability in sales numbers. (I think het and gay male sells better than lesbian.) They used to offer short-story authors for anthologies a $10 advance plus royalties (split between the editor and then between all the authors, so I think a single copy sale nets an individual author something like nine cents). If the book sold really well and the royalties accrued to $100, RR paid the author. If the royalties never accrued to $100, the author never got paid. (I negotiated my contract for a minimum once-yearly payment, but they never showed up so it was kind of a moot point.) Some of their anthos have netted each author well over $100; others, not.
I think they're now going to a flat-fee per story for anthologies, which makes a zillion times more sense because it must be craziness to try and track the royalties for 20+ people for each single anthology title. Cleis, Circlet, and other similar publishers do the flat-fee thing.
The RR contract I was offered was not very author friendly; in fact, it was quite a rights-grab. I don't know if that's changed, but it's not a contract I'd be willing to sign again, and overall my experience with RR hasn't been hugely positive. That said, though, sales do seem reasonable, and the (external, contracted) editor for my anthology is totally awesome.