Palaeodom I've used or set up the following combo's: UST Mavic 819 rims with UST Maxxis X-Mark / non-UST WTB Prowler SS - rims make the job really easy as they are UST specific. Prowler sidewalls leak air for a bit, but otherwise works like a bomb. Side walls are really floppy and soft, but no issues as yet, been running that combo for about a year and onto my second Prowler. X-Mark UST was a doddle to fit (as it shoud being LUST specific - hurt the pocket though) and didn't loose an inch of air till it wore out a year later. Tough as nails tire, just a little weighty, but a fit and forget item. Sealant used was Slime, then cheap Ryder sealant with about 25ml water added to make it more liquidy which resulted in a quicker seal actually. SunRingle Non UST rims with Joe's liners & Non UST Conti Vertical (Gatorskin equivelent - can't remember the name right now) + cheap ass Vee Rubber DH tire non UST, well worn with a couple holes. Used Slime - worked for everything except all but the most stubborn holes in the Vee Rubber tire. But after a bit of a leak, sealed right up. The Conti was actually as easy to fit as the X-Mark above. My mate road that conversion till it wore out. Cross Max SL UB rims with non UST Rocket Rons. What $%*^%^* ball ache to get bead to seat. I will never try and fit Schwalbe tires again, tubeless that is. However, tires and Slime sealant worked EVENTUALLY and are still going. Sidewalls are a little porrous though. A mate of mine did a ghetto tubeless conversion with bmx tube, Sludge sealant, DT Swiss 5.1D's and Maxxis High Roller + Minion R. Was a bit of a bugger to get the ghetto rim strips to seat with the tire + rim and they always leaked at the bead. The non UST tires however never sprang a leak or "burped" off the rim. They were single ply tires, not double ply DH tires if that interests you. I would advise using water based sealant (Slime, Sludge, Ryder Sealant) as its easier to clean up the mess, doesn't delaminate tires like Stan's or Joes does, and it is hopefully friendlier to the enviro.... Likely??? Higher pressures mean you won't pinch flat as easily, but then again that is why you are converting to tubeless and allowing yourself to run a lower pressure for more grip...no? I would imagine the side wall deflects less so making it more suseptible to damage from sharp trail debris (well this is what I tell myself when pumping my tires to 30psi or just less... ). Softer tires are suppose to roll over or deflect around obstacles a little easier and hold grip, not skid across the top? I am sure there are plenty alternate theories... As always it is personal choice, some people won't like the way I ride my tires, but then again I don't like the way some mates run theirs... Experiment with pressures and sealant types, keep a spare tube or two handy and when you do resort to a tube to get you home.....don't loose your tubless valve, they not cheap and you feel like a chop when you can't find it and remember it is on that nice flat rock you found yesterday to sit on while you fixed your tire. OH YES, a compressor is your best buddy! Happy trails