I lusted after an M kit yeaars ago but ended up with the CL kit with the 40 and 90 lenses as a result of doing a favor for a friend in need. Since then I have had chances to buy about every mainstream M body and can afford to do a reasonable M kit but after holding them and caressing them for a time and considering my shooting style and what I'd put in the kit, I ended up preferring the CL. The 40 is in my preferred vof range; I generally prefer the 35-40 mm range over the 50mm but, would like a 28mm to go with the kit but, then I learned to just walk back and most of the time that works for me.
The M body feels large and bulky; the CL dimensions come close to the Barack spec'd sm bodies. I'm not into a large range of lenses as I think generally that almost any Leica beats almost any conpetitor and knowing 1 or 2 lens charactoristics well beats a half dozen lenses in the bag. As for the purported weaknesses such as denting, wind levers, etc. yes, the top will dent a bit if treated harshly. I've never seen or read where someone has actually had a wind lever problem. As for the meter, any camera with a mechanical meter of its age can exhibit the need for a CLA. The camera from my experience is as rugged as about anything out there same maybe the sm body. I've seen many a banged up M body but not sure how abused or used they were so not sure they can or can not take more of a beating and keep on ticking.
I, like some, prefer the meter in the CL and M5 over the led system in the M6 but the M6 metering can be faster but allows less flexibility directly. In comparing the M6 to the M3 and 4, I find it to be clunkier and less well made so if I were to go for an M, it would be maybe a DS M3. But, I also find the SM III series to be closer to the CL in size and concept and 1 with a collapsable lens would be maybe the only combo I'd pick up especially if it required I give up the CL.
In short the CL is as rugged and as good as almost anything out there unless you intend to use it as a substitute for a hammer. Only then do I find the M bode to be the better.