@Minoush, Am using Galaxy S Duos for the last 2 months, and can happily say, its been a fantastic piece for me. No lags, no hangs. I have been using Skype, Mobile Voip, Google Talk, and have never so far experienced any probs.

However, I believe, the choice will be driven by the fact whether u need double sim phone or not. End of the day that would be the decision making factor. Why would you go for a dual SIM phone if you don't need to maintain two SIM's. Alternatively, if you need a dual SIM, then why would you want to compare it with a single SIM phone. As a matter of fact, if you check Galaxy S Duos reviews on www.gsmarena.com, it labelled as another segment of phone altogether!!