e609, e906, e606 for guitars?

i have both the e609silver and the e609black. the silver one is garbage. the black one gets alot of use for me. its smooth and gets alittle more low end than the 57 which is great for some amps(especially crappy amps, the black 609 seems to "forgive" them better than some mics). the 609 black is discontinued and i havent tried a 906 yet to compare the two. ii bet you can find a black 609 used though. good luck.
 
the coolest thing about a 906 is that it is a 609, a 606 and a 509 all in one, at least that's what they say about the presence cut (609), neutral (509) and boost (606)
I almost always use a combination of 57 and 906. the 906 has a it more focused sound than the 57 (less boomy lows and less fizzy highs) and the response seems a bit quicker / tighter.
lately I've been using a combination of 57 off axis and 906 (neutral) on axis and i really love it!

what I heard is that the 906 is similar to

boost=609 silver
flat=409
rolloff=609 black