i did that, and it was the best thing i ever did. fortune favour the brave et al. i think as long as you make sure this is a genuine sale i.e not being sold to multiple parties at the same time then there should be no problems. youve gotta be a real dunce to lose more then a handful of customers when you do the take over. the work i bought would have taken about 10 years to build up myself so was well worth it.
if the work youre buying is something you dont think you could easily get yourself, or replicate in another area then i would suggest you strongly consider it. perhaps keep a part time job to start with until the cash flow gets sorted. most people that sya dont do it are the ones who already have a round they are happy with. getting started is a whole different story and i think you either take risks, or watch it build in drips and draps (the exception being if you are an excellent canvasser that goes out for months and months)