Don't do it! Serious
The people here who tell you that their Leicas last a lifetime don't use their gear for anything, they'll tell you that a CLA every 5 years will keep you M in working conditions. Yeah right, if it stays in your draws that is.
Look I have 3 Leicas and at least one of them is always broken, one which was fully serviced 6 months ago had a complete shutter failure 2 weeks ago, before that another camera literally had parts falling from the inside of the camera into my hand and had to be sent in.
Your G2 is the best and has all the features that the M7 should have without a stinkin' LED blinking inside the viewfinder.
If only I didn't have so much money in that system I'd have got a G2 long time ago!