Well, I've bought 1 Corsair PSU. And I've raised an RMA for it. Not a great ratio. And it'll cost me well over £20 to ship it to Holland (unless someone knows a cheaper way?)
I've also got some Corsair RAM that seems to be faulty (not sure how long ago I bought that). But I've bought a lot of Corsair RAM over the years so that ratio is a bit better.
So good RMA service? Yeah, but would be better if I didn't have to ship to Holland.
Good quality? Not so much, in my case it seems.
(To be fair it's not been confirmed that there is an issue with PSU, but Corsair have said they'll replace it (as opposed to test it)).