[Zig]

Sorry Toad and all: my reply was to a bit of (now deleted) spam advertising a, er, certain male product...

I confess that most of the time I try to have the eminently sensible cash-restraint as mentioned by nt...until the moment I do not, whereupon I allow acquisition fever to dictate a purchase.
As said, though, it makes so much sense in a way to buy an "older" generation of camera: the perceived speed of obsolescence really can work in our favour if we're prepared to wait even a year or so. The NEX-5 particularly has so much going for it, what with its sensor-size and front-end possibilities, given its present upgrade. Yet we do have a trade-off point perhaps with quirky interface and a few other issues.
NT also reminds me of just a few very short years ago: high-end 35mm and medium-format took much saving-up...with the impetus for such discliplining of the wallet being the reliable longevity of what we were buying into.
Now we are somewhat fooled by the nature of what is considered "future-proof": we are on the one hand expected to pay a premium for that which is safeguarded against the future, as if the "future" is some rapacious disease of obsolescence and malfunction, or at least more hard work! On the other hand, as NT says, if one decided to be somewhat left-field in their approach and resort to a combo of film negative processing and scanning, there is absolutely no doubt that superior image quality, excellence of hardware and cheap outlay are all completely achieved for the equivalent outlay on an entry-level dSLR.