I raced a set of Clement PDX tubulars this year. Sliced two of them open beyond repair. Hated the traction, hated how they felt, hated how they handled rough stuff. Finally got a hold of a Challenge Limus tubular. What a difference! Exceptional traction, extremely well mannered handling, great feel and ride quality. I haven't had much chance to check out it's durability, but I have to say - the Limus is far and away many times better than the Clement PDX. I race CX here in the Portland area, and the Clement was made for our conditions. Supposedly. Pish posh! The Limus vastly out guns the Clement PDX.
Probably not the fastest rolling tire for dry, flat, fast courses - but for anything with mixed traction surfaces, off camber, muddy, slippery, grassy - the Limus is your go to tire.
With their massive knobbies, these tires are excellent for muddy conditions. They shed mud well, and they bite into it very well, similar to Clement's PDX. I found them a bit unstable transitioning from mud to asphalt, but nothing alarming, just have to be a bit on the cautious side.
Sidewalls are very supple, more so than the PDX, making it a better choice when having to ride off-camber muddy sections.
Really good mud tire, the tall knobs provide greater traction and turning ability in thick mud, especially peanut butter. They shed mud pretty well, especially if the course hits a stretch of pavement. The limus lets you cut across ruts, rather than being forced to follow the line, especially when leaning the bike over to take advantage of the side and transition knobs. The tread isn't as fast as the PDX on hardpack & pavement, but I prefer the greater traction of the limus in mud. Not the most supple casing, but better than most, go to the TE if you rate suppleness over durability.
Have had good results riding these in mixed to muddy conditions in the Pacific Northwest. Definitely way better grip than the Grifos and I have been able to power up steeps that have others running their bikes. This tire is pretty stable and the few times it has drifted out on me, it caught an edge and the bike stayed upright. I am still learning the limit of these tires, but so far have not hit it.