Brian,
Your grandfather was a wise man. It's one of my favorite sayings too.
Retrofits can be done and they work pretty well in most cases but it is difficult for anyone to guarantee the results for several reasons.
First, unless the person doing the retrofit actually made the bow in the first place, he would have very little to gain, maybe $150 for his labor, and everything to loose, like maybe $800 to replace a nice bow if the retrofit didn't work out.
Secondly, without having made the bow in the first place, it is difficult for the person doing the retrofit to know the condition of the glue joints and of the wood used in the riser.
In a one-piece bow, these things are not nearly as critical as they are in any type of two piece takedown system.
Finally, as I've said before, the most difficult part of a retrofit attempt is to get up the nerve to cut a perfectly fine bow in half. Not many bowyers are in favor of doing a retrofit for that reason alone. I don't blame them.
Having said all of this, I have had so many potential customers tell me that if I would do it for them, they would be willing to sign any waiver I put together. I guess if someone wants it done that much someone should be offering the service. I have heard that Ted Fry of Raptor has done some very nice retrofits and there may be a few others that will do it too. Who knows, when my new shop is ready in a month or two, maybe I'll get the nerve to offer it as a service too.
Your best bet, though, is probably to have a new bow made as a two piece in the first place.
Good luck,
Craig