I had a lot of eggs collected from my ivf cycle (32 actually), and developed OHSS, so never had a fresh transfer. All embyros were put into storage..

I got a BFP on my 2nd FET transfer (DS born April 2005)
I got another BFP two FET transfers after that (expecting a girl Nov 2006)

So, i see no problem with FET's, 50% success rate for me Almost 2 years between embryo storage and my last FET.

All the best