Of late I've been considering buying a set of these & of course going to have moulds made etc. I have looked at ACS & Etymotics, there are others out there, but these 2 brands are standing out from the crowd as such. Anyone else gone down this road, any experiences with the brands. I've also looked at buying some Etymotic ER4's & use the ACS sleeves, but not too sure its worth it as the single driver ACS units are practically the same price as this route & that's custom moulded. My concern is, with exercise do the customs fall out, I'm not sure they're as snug as I require, which may lead to overhead types again. Any info from experience would be appreciated, TIA.