I didnt test on a 1st Gen device. The co-creator, Jeff, tested on 1st Gen but I never saw it. However, I personally thought it was kinda slow on the 3G (others say its just fine). In my mind, what is perfect is playing on 2nd Gen Touch or 3GS. We debated whether we should do different deployment. Future games will have a button or auto-detect the model and adjust. Yes, there are ways to adjust sound and graphics to get more fluidity. On 2nd Gen Touch and 3GS, you dealing with 60-80 fps. Its SUPER fluid on 3GS, far more than even other games without the BioReplicants but similar polygon count. I optimized the balls out of our core-engine. It very efficiently parallelizes matrix multiplications etc., (I take good advantage of the VFP unit... hint hint, get out your assembly books).
