There are no value digital RF cameras. M8 is crop sensor and may develop the screen problem. Leica will offer an upgrade for a price you will not want to pay.
M9 has sensor corrosion which appears mostly in hi humidity conditions. So far they are willing to repair free. Future ??
M is expensive and best long term solution.
Epson may or may not be good and repair is a big question.
ME is same as M9
You need to pay a lot of $ to get in the game. Digital Leicas all will have longish term repairability/parts problems. Their solution will be for you to pay for an upgrade.
Budget digital is Nikon D3300, D5500, D7200, D610. All these will take very good photos with much less investment but are not RF cameras.
There is no reason to buy Leica unless you already have lenses and they are modern and coded so they focus properly. Old lenses may need to be recalibrate.