I started using the Primos True Double a few seasons ago, and fell in love with the stacked frame design. I picked up the Boss Hogg last weekend, and it may be my new favorite diaphragm. They are so much easier to work than a traditional diaphragm. I'd highly recommend that you try them if you haven't already. As far as friction calls, obviously I'm partial to the ones I make. I prefer my Purpleheart glass over slate. It's hard to beat a glass over slate in a pot made from harder woods like Purpleheart or Osage.