To be honest, I'm on the fence right now. Last month I picked up a cheap-o break shaft for my Meucci. I think it was $35 shipped to me. I'm just thinking out loud here, but by the time I fork out another $50-$100 for a spare butt just for the break shaft, I probably am close in price to the cost of a real, dedicated import jump/break cue.
I guess my thought was that if I could find another brand of butt, that had a bad shaft that someone was looking to get rid of cheap, it might be worth picking up to use for that break shaft.
But when I boil it all down... My entire motivation for this is just so I don't have to unscrew one shaft and screw in another when playing. So, I have to really think about what that amount of convenience is worth to me!
Have I mentioned that I'm hopelessly indecisive?
What kind of butt would you be looking for?
Type/style/weight? Joint collar material? Price range?
I think it's a cool idea. A good break shaft can go with just about whatever butt you want I think as long as the joint diameter isn't too different.