The only real upgrade I can think of to the newer version is that you may want to make some braces for the Y axes. It will be easy to do with the machine and shouldn’t take any disassembly. I made some out of 1/8" aluminum, and they work just fine: Y Axis Braces and Belt Dust Shield
Other than that, it looks like the new version has the rest of the upgrades covered. They were never “recommended” upgrades, they were just “suggested” since they increased the machine’s ability to cut faster. An unmodified original X-Carve could still make the same projects, it would just take a while longer because the cuts had to be made slower and shallower to minimize flex.