Thanks for all the very interesting replies.
I did sell the M8, although I loved the camera. I don't think it does well at high noise, and although I never had any really major issues, the 5D has been more reliable. Discovering the ability to use 3rd party lenses on the 5D, the higher useable iso and the launching of the 5D mk II all lured me back toward the canon and I could not justify owning two expensive cameras, My M8 has gone to a good home and I will continue to use my film M6 and some M lenses. I also bought the LX3 which I think is a great compact if you want something small to carry around when the Canon (or even at times the M8) is too big.
I agree with some of the comments about zooms. As useful as they can be, especially for professional work, when doing my own creative work I prefer to get the lens which produces the best image and that is usually a prime lens. Plus I quite enjoy the discipline. I do think the 70-200 f2.8L lens is as good as just about any prime, but it is such a heavy beast (I lugged it across Lao before) I would rather not take it with me).
I have recently been testing various third party used lenses I own on my new Canon 5D Mk II. I have nothing against many of Canon's finest L lenses (my favourite of the moment being the 35mm f1.4L), but sometimes find other lenses have a special 3 dimensional feel and smooth bokeh. I love my Leica Summicron f2, for example, far more than the Canon 1.4 which I find quite brutal at f2. I have a few very nice Leica R and Contax/Zeiss lenses I can use on the 5D. Reading various forums made me look into Olympus Zuiko lenses too, a cheaper alternative. I bought the 21mm and 28mm f2 lenses on ebay. Both very nice lenses but the 21mm is nowhere near as good as my Leica Super Angulon 21mm f4 (at f4, f8 or f16 in my opinion). The 28mm, on the other hand, is a great lens.
So, on the eve of a trip to Myanmar I narrowed down my travel options. Leica 21mm f4 (I compared it to my Oly 21/f2 and it was far better throughout the aperture range), Oly 28/f2 (which, on the other hand, is flawless), Canon 35L f1.4, Leica Summicron f2 (far, far nicer than the Canon 1.4) and Canon 135L f2 (another great Canon lens).
Then - just tonight - I noticed an old second hand Olympus SLR on my shelf I had picked up for about #60. I wondered what lens it had on it. Sure enough it was the Olympus Zuiko 50mm f1.8. I tried it on my 5D mk II straight away and was immediately impressed. I then quickly compared it to the Leica Summicron and found, to my shock and disbelief, I think it produces better images than my Summicron, and even a smoother bokeh. Whilst it is not engineered as well as the Leica, it is half the weight and tiny. So the Leica will say at home and the surprise find, Oly 50/1.8, is coming on holiday to Asia.
