Here are a bunch of details that might help weigh some trade-offs. First, the PDX tread pattern is fantastic. You can run these in dry conditions, or mud, or in-between. A file tread would roll slightly faster dry, but these are nearly as fast. A full mud tire would hook up marginally better in full slop, but these hold their own (and don't pack up as there is lots of space between the treads, which is key). On a course with some mud, some pavement, some gravel, etc, the PDX can't be beat. Now the variations. I loved my old, non-tubeless, foldable, 120 tpi PDX's. They were super supple and 270g (add 90g for a latex tube) but of course couldn't go too soft w/o worrying about pinch flats. Then earlier this fall I briefly had a Clement-branded PDX tubeless version (probably mfg'd roughly a year ago but sold in 2018) which weighed in at 430 g (not including the Stan's sealant I used) and had a much thicker, less supple casing than the non-tubeless version. First hard use (a CX race at low pressure), I somehow damaged the casing (never done that before - I'm 150lbs). It had no visible cuts or tears, but it had developed a significant bulge at one location (yes it was seated evenly). Finally I got the currently-selling Donnelly-branded PDX tubeless version. It's 495g on my scale. Yikes. The casing is even thicker, quite a bit more slipperyplastickyrubbery, and less supple than the older stock Clement PDX tubeless. The ride quality is comparable to the older tubeless version and not as good as the much-suppler, lighter, grippier non-tubeless 120tpi version. Both the Clement and Donnelly-branded tubeless specimens mounted tubeless w/o an air compressor on Ritchey WCS Zeta Disc rims, however both allowed some air to escape for a number of days despite sloshing a fair amount of sealant around in there, as evidenced by air bubbles coming thru the casing when viewed underwater. That's my experience. Hopefully they'll make a race-worthy tubeless PDX soon.