Perhaps all those fancy cues the OP has was intended to be shot by the original shafts by the cue maker. If he is being so demanding over weight and balance then one can argue those cues were made with its original shaft and balance for a purpose. What Tim Scruggs deemed as a great hit and feel will be tossed out the window with a KW shaft.
Putting those KW shafts on something doesn't make it instantaneously better. Unless the cue maker, himself, intended it to be hit and be played with a KW shaft.
I have a friend who wants to put a carbon shaft on his 7k cue, loaded with natural and silver. LOL Its his choice at the end of the day but I just find it defeating the purpose. You can just buy any butt and throw a carbon on them and if you can't? Then the cue maker didn't design the cue for that purpose.
If someone let me shoot with their Black Boar then I hope they put the BB shaft on and not a Chinese or Revo shaft. LOL
Then again, I think its blasphemy to put an aftermarket shaft on a custom cue.