Mel,
To be quite honest, the manufacturing process and quality of tubing has progressed so quickly in Aluminum that a mass produced Asian frame that sells for $200 wholesale will be more reliable than the old Mani.
I guess the question you have to ask is "Why do I want this frame?"...is it because it is a vintage piece that will warm you heart during the build and each time you look at it thereafter? Or, as you say, if you actually plan on riding it, will you always be holding your breath in concern that a new crack will develope dissapointing you?
As a piece of MTB history, the Manitou frame is a pleasing eye turner...as for ride quality and reliability, it leaves a bit to be desired.
cheers,
rody