^ +1, the A4 SM would most likely be a bit sweeter and closer to what you're used to.
however, before ditching the Mule, try a couple of things...
(1) you could (as Hunter said) cut/unsolder the capacitor connecting to the neck pickup's tone pot - this will give a slight lift in the treble frequencies. I'm not sure it would change things enough to get rid of the dark tone you've got though, but worth a try.
(2) make sure both the tone and volume pots are both 500k. if they are and the neck pickup is still to dark, then a 1M volume pot will almost certainly solve the problem and give you a much brighter tone. It'll only cost a few quid for a pot inc postage so it's a cheap mod. trust me, this will give you a much clearer tone (I did this with a dark neck humbucker in my Tele)