i think this can be a good idea. at least the more melodic tracks can be in a certain key which changes when you pitch them up.
(different topic -> mixing in key)

see these links:

http://www.mixedinkey.com/?gclid=CPm...FQoOUgodIxHCwQ

and this

http://www.beatmixing.com/harmonic.html

what works with what (useful for production as well):

http://www.harmonic-mixing.com/charts/keychart.mv

demo is very useful. you can add a little sticker with bpm/key to your records if you like :)

actually i think when i make a track i produce it say at 140 bpm. i may sound stupid but then it is made to play at 140 bpm +/- not at 140. i would have set the sequencer at 145 if i wanted it like that. difficult subject i know because others might like it at 145 bpm or 137 or so.

.. but i don't play out to public so...