I'm using KoolTack. Was using RagMount before but the KoolTack has a fraction of the dwell time of everything else. 30 seconds once the press has reached full pressure and you're done and the temp is 150-160ยบ vs. 180-190 for RagMount. You'll have to buy a case of the stuff to use it though, it's not a separately sold adhesive, it's sprayed on to the foam core itself (which is REALLY nice). They use Artcare Archival for the foam board (which I prefer over Gator, this is what I'm using in my lab for mounted prints).
Cheers, Joe