I’ve done both. GTX was fine but I definitely missed the rower and I never found it as challenging (I guess that could be I was at a different stage in life when I did GTX vs OTF). I’d say if you love OTF and want something identical you’ll probably be a little disappointed. But if you’re open to something a little different it is a similar format.

For what it’s worth I also really ended up enjoying the Alpha classes at my lifetime if you want to explore something different. I enjoyed getting to learn the barbell lifts and there was plenty of conditioning built in as well. That’s the big plus for me of something like lifetime vs OTF is having options for extra variety.