I have to disagree with Rami in part. Different instruments bring out in me a desire to try different types of music. The setup of one instrument may bring out my desire to play some slide while another instrument may inspire me to play some Swing, et cetera. So having a variety of instruments keeps me more motivated to practice and it gives me options which allow me to shift focus when I feel frustrated and need to try something else for a bit. All of this encourages practice; which improves skill. JazzyVee said something similar albeit with a different spin. The phrase which does not impede your performance is a critical point.
My Alembic is my least played guitar because it does not inspire me as much as my other instruments. But when I am in an Alembic mood it too is a source of inspiration.
Getting back the Neurotictim's question about too much bass; I think that extremely versatile but correspondingly complex active electronics can be an impediment to some players. The old joke which basically states beware of the man that owns only one hunting rifle... he probably knows how to make it work in every situation comes to mind. However I do not think that one can have too good a setup or too good a teacher.
But some people are better suited to having 1 volume control, 1 tone knob, and 1 pickup switch. Give them a parametric EQ and multiple Q-control presets, and it distracts them from focusing on their basic playing technique. A warehouse full of auto-shop tools you are not comfortable using will not help you if you really just want to learn to drive a car. However: comfortable seats, an ergonomic cabin, and user-friendly controls will make you a lot more willing to practice your driving.
I would rather learn to drive in an obsessively maintained Rolls Royce than a jalopy with no synchronizers in the transmission and really bad brakes.
-E
(Message edited by u14steelgtr on March 01, 2008)