before making the jump and investing all that money on a digital Leica, do you have any experience with RF cameras?
reason I'm asking is because the shooting approach with a RF is slightly different than with a SLR, especially since you're only seeing a representation of your image through the OVF and not the actual image itself.
the easiest transition would be getting the newer M240 since it allows you to use an EVF and thus have live view just like the Sony A7II but this is also the most expensive as well.
you could get a used M9 for half price, but ISO1600 and higher is not great, older, slow buffering and rear LCD is antique, plus no live view like the M240
but most people including myself prefer its CCD sensor over the CMOS on the M240.
another way to get into a Leica is by shooting film first, you can find old M cameras (2,3,4,5,6) for under or a little over $1000 or even cheaper is by getting a Bessa R for around $300-500
me personally I'm shooting film Leica only and have the A7 to shoot my M lenses but airfrogusmc might be able to chime in his experience since he's also moving from DSLR to a digital M camera.