Interesting thread. I'm liking the way Chris laid out his answer and mostly agree with those %s. The one thing that's very interesting......the "joint" would seem to be one of the lower %s as many would agree, but ironically it's one of the first and biggest points of concern/preference that people have when buying a cue !!
The below percentages are my opinion on pro tapered 13mm maple shaft cues with maple or other medium weight wood butt.
Butt 10%
Joint 10%
Shaft 20%
Ferrule 25%
Tip 30%
Other 5%
Percentages are impossible to give accurately. Because any of those things can change the hit a huge amount if you go with various materials. A super hard or super soft tip becomes 80% of the hit. An Ebony forearm could change hit dramatically from maple. Change to a purple heart shaft and now maybe 60% is in the shaft. So there is no way to give an accurate answer.
Lots of great points. I forgot the bumper and have a friend that bought a specialy designed one and raves about it.