Got my gear today (Oxtar boots, JR jacket) and took an evening loop of the SD shoreline this evening for a few hours (80 miles).
Very very happy with the fit. If any other "big guys" are nervous about JR fitting, it was great, and even probably slightly LARGER in the mid section/gut than the measurement chart, because the 4X is actually kinda big on me (a welcome change). I could have squeezed into a 3x as I keep shrinking (thank god).
HOWEVER, the Oxtar boots went from being a half size too big (TWN's feedback from his pair) to "oh my god barely fits me" snug. I wear and 11 shoe, 10.5 tennis shoe if I want a really snug fit. I got the 45 boots, which say they translate to a size 11 US. Let me say I BARELY get them zipped up. Yes, I have extra meat on my shins, but it's tight even further down where body fat isn't an issue.
Be careful when ordering the newer, resized Oxtars! If I put a thick wool boot sock on (still have about 35 pairs in my infantry gear chest), I don't think I'd get it zipped up. Maybe they stretch a bit with wear.