The hairline is great on the New Generation system! It just diappears. I ride bike, do yardwork, swim, etc. and I've never had a problem with sweating. Not sure how you'll react with a heavy duty workout since everyone is different but the nice thing about skin bases is that they're easy to remove, clean your scalp and reattach. It's been written on this forum many times that lots of people use 'Got To Be Glued' spikey hair spray to attach the New Generation base. Since the New Generation base is so thin it 'vacuums' itself to the scalp and very little adhesive is needed. That's why the nominal amount of stickiness in the GTBG hair spray can do the trick for a 2-3 attachment.
Regards,
John