My DD13 has it 2 days/week. My DD17, a Senior, takes cyber gym, as do many in her class. As she's in Marching Band, she's exempt from the cardio part, so she need to record and have confirmed 15 hours of strength training in the 1 semester of gym. Plus many hours of PC-based training/testing. Frankly, it's much more work than actually taking gym, but she wanted room for other classes.
Regarding skipping, I would also recommend the IAS. If nothing else, it provides a lot of things to think about and helps quantify at least some aspects of the decision.
From a personal perspective, I skipped and never had problems.
