Some thoughts a.k.a. my two cents. Addressing the bass-ics of design...
The reason to have a nut which is narrower than the bridge is ergonomics. The following descriptions are deliberately over-simplified and are intended to convey only concepts.
When you are fretting near the nut and your fretting hand is further from your torso than it would be if you were playing further up the neck the positions which your wrist can easily assume are more limited and a closer-together string-spacing makes it easier to play.
The arc of a strings vibration is greater at the mid-point between the nut ant the bridge than it is toward the nut and bridge. Nominally the lower the note/frequency is; the greater the arc of a strings vibration. So to keep the strings from coliding with each other one builds the instrument with a bridge that spaces the strings far enough apart that the strings do not collide.
The string spacing at the nut and bridge is a compromise which is derived from a lot of factors including:
* how much joint articulation we can comfortably realize
* hand size
* fingertip size
* finger length
* string vibrational arc
* personal preference
* what we are used to (whether or not it is truly idea for you)
* scale length plays a small role too
So a mandolin which has a very small vibrational string arc could theoretically have a neck that was 5/8 wide and the strings would not collide with each other when they vibrated. However we build the necks wider so our fingertips will collide with each other less than they would if the neck were 5/8 wide.
On a side note you might want to think about how much if-any spiral-twist you want the neck to have (do I have your attention now?). I have a 6-string where the entire length of body and neck are built with a substantial twist to reduce wrist-strain when one is playing closer to the nut. I will include a picture of it here and you can see better (larger & clearer) pictures of it at:
http://fj45.com/Instruments/Leo-Burrell-Guitar-Info.asp This twisted configuration really works (for me). It is probably not something that you are currently used to (or at least not as a desirable attribute).
The above mentioned suggestion of having multiple profiles and rotating them is great. I like to play everything that I have a chance to try out (from the best to the worst). Sometimes playing the worst of instruments enhances our clarity about what we do not want EVER!
I hope this helps and contributes to your ordering what is and will continue to be ideal for you (even if it is not what you are accustomed to currently).
Regards
-- Eugene
(Message edited by u14steelgtr on December 29, 2006)