Thanks for the responses everyone. Good things to think about. Didn't realize how big a jump the M9 to M240 was; when it came out, I was still fussing over the dreaded "DRIVE BLOCK" error.
I'm not a high-ISO chaser like a lot of digital camera buyers (or I wouldn't be looking at decade-old cameras), but while the M8's noise can be lovely in certain situations, especially BW, its hard to work with a lot of the time.
Considering some of the replaced-sensor M9s I've seen approach the cost of the M240, I think the latter is in my sights. I'll miss the black chrome, little battery display screen, and a RF just doesn't seem an RF without a bright line window!
I'll also say I have looked at switching to another system with adapters, namely the Fuji XPro. I'm still not sold on EVFs; the only one I've felt came close to an optical experience was the Leica S series, and obviously that is far beyond my budget and desired size. Still a film shooter at heart and a real RF is close.