You'll hate me for saying this, but my ItS hybrid stabilized at around 2-3 hours but dropped again after that and is still dropping at the 6 hour mark. I'm now at 14.8% tension loss. My best guess is that the gut is losing about 9% and the poly is probably at around 21%. If I didn't use RacquetTune I would never suspect it. I still like the way it plays. I can see why some people think Iontec is good at holding tension because you can't tell what is happening based on how it plays, but the numbers don't lie. If my hunch is right, then its tension holding capacity is mediocre for modern co-poly at best. I do like the feel and dwell time, so it's possible that I'll stick with this setup if I don't find anything better. I'll probably keep the tension of the gut and poly the same since I don't want the difference to be any bigger than it is after the poly tension drop.