I have a hard time believing you get the same muscle adoption as free weights.

Also there has to be a mental loss with lifting to failure if you know there is no failure with the bar. If I know the machine is always going to be there I don't think I push as hard. I always lift heavy with a spotter but that person knows to let me go until I fail.

I think my other mental hurdle would not physically seeing the weight on the bar. I like looking at my bench and seeing 3 plates as I bench. It's the meat head in me. Seeing a number on screen may prevent me for pushing.

Again, I've been interested in it for a while but because of the things I've mentioned never pulled the trigger.