2017 FE501 vs. 2019+ CRF450X?

How's it going? First time here in the offroad section. So I'm definitely a track rat, but I've been finding myself in the desert more and more the last few years, camping with family and friends and I'm looking for a dedicated desert bike. Currently I have an '03 KX500 that was all dialed for the track, and I've got a spare set of wheels that I use for the desert and it does the job, but I'd like to keep the hours off of my beloved KX500, especially desert hours.

I have the option of buying my Pops 2017 (plated) FE501, it has ridiculously low hours, and it has all sorts of upgrades. The guy he bought it from went absolutely nuts at 3 Bros and in my opinion, the only upgrades it would require is to swap the JD Jetting dealio for a Vortex ECU, and have the suspension set up for me. Recently I borrowed his FE501 to do a Barstow to Ridgecrest and back ride with my friends and I loved the power, and the 6 speed trans, but I had the slave cylinder oil seal fail and I was lucky that we were able to pull off a trail fix at the Husky Monument. I also hated the amount of work an oil change required and I didn't care for the build quality as far as how the plastics fit and the oddball hardware, etc.

Being a Clydesdale sized dude who can handle all that a KX500 or FE501 have to offer, would a CRF450X offer enough throttle happy factor for me, or would I be wishing I had pulled the trigger on the FE501? What about a big bore kit for the 450X? What are the main pros and cons between a FE501 and a CRF450X? Also, the plated or non-plated isn't an issue for me as I wouldn't be riding on the street at all.

Or is there another option that would be better, like an XR650R with an upgraded front end?!

Thank you for the feedback!