If you have the cash to spare (like someone else in these forums who said that ""budget is not a problem"), by all means do take the plunge. I would say that you do get what you pay for, in this case.
However, if you have reason to be more cautious in parting with your money, do remember that there are many other factors to consider than high ISO performance. Firstly, as already mentioned, the price of the camera body is tremendous compared to consumer/prosumer level digicams. Are the features worth that much to you? Secondly, with an SLR system, you're going to be investing even more money on fairly expensive lenses. Are you prepared to do that? Thirdly, don't forget that the physical form factor of 35mm lenses is comparatively bulky--getting the equivalent of your F707's 38-190mm 5x zoom lens is not a small matter (literally). Fourthly, digital camera technology is still very fluid at this point in time, and things are getting both better and cheaper month after month; who knows, before long the kind of performance we're seeing on DSLRs today may well be commonplace on lower-end digicams. Are you willing to accept the risk of 'obsolescence' and thus of diminishing returns from your hefty investment?
If you ask me--this is my personal opinion only--digital SLR technology has not matured to a point where it is worth it to plunge in unless you really have sufficient disposable income to spend. They definitely do not qualify as worthy long-term investments at this stage. For me, I am content to stick with a "prosumer" level digicam and wait for some proper standards and technological maturity to emerge in the DSLR market (no more of this "more and more megapixels" thing, please). For low-light action shots, I personally feel that 35mm film is still the most cost-effective solution. Once again, this is just my own S$0.02's worth. Hope this provides some food for thought.
Thats for scenery, people shots at night must use flash. 
