This question (if I buy a Leica or a Hasselblad, will it be just as good as some larger format?) seems to come up on a number of lists, and it's interesting to consider what motivates it. I suppose that it's dissapointing to discover that one can get "better" results with a TLR (or Crown Graphic) that costs a few hundred dollars than with a Leica (or Hasselblad) that costs thousands, or that if one wants the results of a bigger camera, then one has to lug around a bigger camera.
But really, I don't think it's necessarily a useful comparison to make. A Leica is probably the best 35mm rangefinder camera, and 35mm rangefinder cameras do certain things very well. They're fast and quiet and have fast sharp lenses and can take 36 exposures on roll, and because of the format they are easy to prefocus and handhold and fit in a pocket or a small bag.
But there's no particular reason to use a rangefinder camera for landscapes or architecture, and they're really lousy at macro and telephoto work, and wouldn't be a great choice for still lifes. And an SLR or TLR is probably better for studio portraits. That's not to say that one tool can't serve many purposes, but there's always a tradeoff when you use a pipe wrench to hammer a nail. I like having a variety of tools and use them for what they do best, but sometimes I'll accept that tradeoff, like using a view camera for portraits. The view camera is not as dynamic as an SLR or even a rangefinder, but it produces a big retouchable negative with exquisite detail and lets me use classic lenses as they were intended to be used.