It does not require an advanced accounting degree to figure out that two camera systems essentially double the cost. There are some synergies such as using the same lighting equipment, tripods, bags, memory cards, computers, etc., but for the most part, two systems equal two times the cost. Right now the spend-o-meter is at an all-time high after buying the Zeiss ZE lenses, followed by the Leica M9 and then several Leica M ASPH and APO lenses. Consolidation is coming, but deciding which lenses stay versus which lenses will be sold is very difficult. Everything could be consolidated to the Canon 1Ds Mark III, but I have been there before and the downsides include:

1. •The Canon 1-Series body is a big, heavy and draws attention in public. I have tried many other Canon bodies and the 1Ds’ yield the best image quality (ie - dynamic range, color separation, contrast, etc). The 1Ds Mark III is not a practical choice as a general use, “carry it with you” camera.
   

2. •A Canon dSLR needs Canon sized lenses. My de-facto kit is the 24-105L IS, 70-200/4 IS and the Zeiss 100mm F2 Makro Planar ZE. Add a 430EX II, the 1Ds3 itself, filters, spare battery and the bag total to about 15 pounds... whew... not fun.
   

3. •When the Canon system is my only system, I tend to augment the Canon lenses with Contax, Leica, Hasselblad and Zeiss lenses. This results in a collection of manual lenses and a set of Canon auto-focus lenses, effectively doubling the lens cost.
   

The crux of the argument is - the Canon 1Ds Mark III is a large camera, compounded with large, heavy lenses. In contrast to the 1Ds Mark III, the Leica M8 / M9 are small and relatively light. The Leica M9 files are easily on par or better than the Canon 1Ds Mark III files at low ISO. The Canon and Leica files are different. Canon leans to the yellows and reds with a warmer look, and a somewhat bolder contrast. The Leica M9 colors have a pastel bias, more cyan perhaps, maybe a cooler look. The M9 tends towards blue much more so than the Leica M8. The M lenses have a lighter, more delicate contrast. Shadows are generally more open. While I like the Leica M9 (and the M8), there are limitations:

1. •Unlike a dSLR, a Leica M rangefinder is not a TTL system (through-the-lens), so it is difficult to imagine or guess how the wide convergence will play out. Framing can be hit or miss at times too. It comes down to taking a picture and checking the LCD, then reframing and repeating - sometimes it feels like trial & error. Optional viewfinders help can help with framing on the Leica M, but overall I prefer a SLR and a TTL viewfinder for wide angle shooting.
   

2. •The Leica M8, M9 and lenses are not weather sealed. At Niagara Falls the Leica M9 was protected from the mist by a lens cloth. In Alaska I did the same with the M8, and also kept it in my jacket. In Alaska the M8 viewfinder fogged up and was impossible to focus. No problems at Niagara Falls, but I was worried.
   

3. •Rangefinders are limited to a maximum focal length of 135mm depending on one’s eyesight. Viewfinder magnifiers help, but in my experience there is a trade-off in contrast. More importantly there are no 200mm or 300mm lenses (barring a Visoflex, but lets not go there).
   

4. •When it comes flash photography, the Canon systems are eons ahead of the Leica M system. If fill flash is needed, it is a Canon day - no if’s, and’s or but’s about it.
   

5. •The M9 lacks modern goodies such as sensor cleaning, Live View, good ISO 1600 & 3200, battery life, video recording, universal file support, dual memory cards, etc.
   

The Canon 1Ds Mark III and Leica M9 fit well together - where one is weak, the other is strong. The anchor lens in my kit is the Leica 50mm Summilux-M ASPH. Another anchor point will be the Zeiss 100mm F2 Makro-Planar ZE on the Canon 1Ds Mark III. The images in this post are intended to illustrate the size differences between the Leica M system and the Canon EF system. To say one system is better than the other is not fair. Both systems have their strengths, and for the most part I think picking a Leica M system (over a dSLR system) is mostly based on personal preferences. If the decision were based on specifications and technical goodies, today’s dSLR’s easily win. So the Leica M9 is more about, “I got to have it!” - and the key question is - are you willing to pay the price of admission?