Short Sale ethics/strategy for buyers

[Bienes Raices]

(I wasn't sure if I should put this here or in the short sale forum. I think it's more of a buyer question though)

I don't know about other people here, but in my area it now seems to be about 10 short sales for every REO, and the REOs that are decent tend get overbid quickly so that they are not good cash flow deals for rentals.

Which leaves the short sales. I used to avoid them like the plague but now they seem to be the only option. I currently have two SS offers accepted by the sellers, one accepted one month ago, the other six months ago, and I'm wating on both. I try to put in a lot of offers but I'm not prepared to buy every single short sale that gets accepted by the bank (if it is ever accepted at all).

I've been told that I will ruin my reputation if I put in multiple offers on different short sales and then back out of some of them because an REO comes along or one short sale gets approved before the others, and that I'm screwing over the seller because they may lose their house if I back out. But I'm having difficulty with the idea of just putting in only one SS offer and waiting. It might not go through. Or it might take eight months to go through. That does not seem to be a good strategy for being a successful investor. It's not an efficient way of doing things.

What are other people here doing? Are you waiting for REOs and making higher offers? Or doing the short sales?