Ok, Jato. So, in my o.g. KLR 1.9/4.70/1.70 (SKU: 19KLR-R) I ran C.I. lil' nova dual stage foams with comp cut inners and soft front/med rear outers (CWR-2024 and CWR-2025) They come with a "tuning ring" that is a 3rd layer of foam (not to be confused with the "tuning discs"), I didn't use that on the smaller tire. On the KLR X4 1.9/4.75/1.4 (SKU: ott-klr-x4r), I use C.I. lil' nova dual stage foams with comp cut inners and soft front/med rear outers with the "tuning rings" (CWR-2014 and CWR-2015) that I narrowed with a bread knife and followed with a dremel. I tried the same approach with the X4 & the 4.5 inner first and I thought it filled up too much of the tire.
The red compound is the same on both. The X4 does feel like it has more sidewall support (than the o.g.), though as it's focused down at the bead are I don't think it's all that effective. It was definitely not supportive enough to run the 2 stage (open cell) foams from Voodoo that were recommended for them.
Both sets of tires are prone to wear, but that's to be expected with the soft compound. The short set had six months on them before they got put through the paces at Axialfest last year and still emerged from that as usable tires, albeit maybe reversed now.