Image quality is worse with DSR. DSR is kinda like FXAA's slightly more attractive cousin that weighs more. Play with DSR on for a bit and then try supersamlping 1.5 or 2.0, whichever let's you have the more desirable frame rates, and see if you can spot the difference. You'll still have aliasing to deal with while supersampling but with SMAA from sweetfx it is cleared up for the most part. SMAA also creates a minuscule amount of blur on the textures unlike FXAA or what you get with DSR. Ditch DSR and use SMAA over FXAA in your games; your eyes will thank you.
Personally I find DSR to give a superior image. I use the optimal settings recommended for my system by GeForce Experience and haven't had any problems, even though I'm pretty sure it leaves anti-alisaing on. Though I haven't tried manual settings. In fact I haven't even seen them! I tend to just use the Experience software and the Gigabyte OC Guru software that came with the card.