Personally, I want a fit that is as close as can be to what I ride outside. One can develop bad habits regarding body position, they can be then be transferred to the position on your outside bike. Conversely, with the right set up, improvement can be accomplished with a bike on a trainer. I am not much concerned with the frame material, component quality level or wheels/tires. Having said that, I have done no indoor pedaling/spinning in a couple of years. I do not like it, I refuse to call it riding. That's just me.