I bought a HT 29" about 1,5 months ago that was equipped with 2,2" X-King tires front and rear. (The Race Sport version)
I live in Southern France, where the trails have a lot of sharp lime stone edges that make tire durability very important.
On a local race course for a duathlon (10km trail running + 20km XC), I punctured the rear tire on the first recon ride on the course.
I changed the rear tire for a Race King 2,2" (Race Sport version as well) and converted it to tubeless.
On the second ride on the course, I tore the side wall of the front in a rocky section.
On the third ride, I punctured the rear tire again.
The Race King rear + X-King front combination was blazing fast, but absolutely worthless in terms of durability.
I understand that the Race Sport version is the least protected out of the range, but still.
I bought Maxxis Ikon 3C TR 2,2" (front and rear), but at this time of the year when there is fair amount of damp ground and mud on the trails, the Ikon didn't have enough grip as a front tire.
The Continental tires came in at less than 500g per tire, while the Ikons were 594g each, so there is clear weight penalty. It could be felt in the uphills, but durability was just not sufficient.
I am actually riding a hugely porky Mavic Crossmax Quest 2,35" on the front now, which is 810g!!!!
Went a bit off topic, but if you wonder between RaceKing and Ikon, the RaceKing feels faster, has a little bit less traction in corners (in the dry), but is surprisingly grippy in technical climbs, even when rocks are a bit slippery. As a front tire, the X-King is wonderful!
The Ikons, just like the RaceKings (and other really low tread tires) are very sensitive to finding the right pressure. I noticed that when I ride the rear tire at 1,9 bars in tubeless, the grip is much worse than at 1,8 bars. At 1,6-1,7 bars, I feel the rim taking hits.
I know it's a bit old school already, but the Racing Ralphs, while wearing quickly in rocky terrain, are still an amazing combination of fast rolling and good cornering.
Wow... this turned into a non-structured post. Well, hope you got something out of it.