Some additional bartolini dimensions and descriptions:
http://www.bartolini.net/information..._bass_pu_s.htm
And some information on fairly new preamp that lots of people are talking about
:
http://audereaudio.com/
Basically...from what I read...the bartolini preamp will "color" the sound in a way that some people really like. The aguilar will "color" the sound less than the bartolini preamp. And then the Audere will color the sound less to not at all.
Search for emg and bartolini, then search for aguilar and bartolini, then search for audere and you will be able to read for days and days...
Good luck. This should be fun. I hope you can enjoy this journey and hope you end up liking what you get.