My biggest fear of going to a MC is that I don't spend enough to prevent it from being a lateral move. You definitely have a good phono pre.
I was thinking the same thing and wondering , do I have to spend $1500 on a cartridge for a just a modest improvement? Not sure I want to do that. My biggest improvements since getting back into vinyl were the accessories to dial things in better. Stylus Gauge , MoFi Geodisc, VTA block . After some trial and error sound improved dramatically.
If you go with another Rega , the 3 screw mount system takes a lot of fuss out of the equation. If not a mirror protractor or geodisc is an easy way to get good results