I got a 609 a little bit ago and recently used it on a guitar amp for a live session at my studio/church. So far, so good.
I haven't gotten a chance to really iso the mic and compare it to my 57s and 421s (sorry, no 906), but will do so. I got it for an extra flavor to those two mics on guitars and toms.
I'll be trying it out on toms soon.

I too am interested in how it varies.
I'll report back w/ more specifics in a few days.

Unfortunately I don't have a 409 for comparison, but I own each of the other two. Both are nearly foolproof on guitar amps. The e906 has 3 EQ curves built-in so you can alter it's brightness. Even without hyping the 5kHz presence the e906 is a little more articulate in the mid-high range than the e609 - but the two are still pretty similar overall. If you were just looking for something comparable to a 57, or just using it to mic a guitar rig, it would be hard to justify the extra money for the 900 series.

I'm not a big fan of the 'hang it over the cabinet' approach. If you want any subtle mic positioning in relation to the speaker cone you'll have to put it on a stand. Hanging it might be tolerable for live use with a combo with a single speaker.

Good luck, you can't go wrong with either.

I have experienced the 609 ina limited amount and it was really a good sounding mic. Very much an 'instant' guitar sound. Since it was what was called for at the time there was no chance or need for that matter to tweek it. I guess that would be a good thing but my experience was limited.

Never heard the 906 but have heard good things from those whos ears I can trust.

The 409 is one of my ten most favorite mics. I include it with the Beyer 201, theShure SM57 and the SM81, the Neumann U87 and the KM84, the Audio Technica 4033 and the ATM25, the EV RE20 and 27,and the MD409.

With a couple of these each you can record anything with quality.

I have never A/B'd the 409 with the newer versions, but after spending a lot of years with one (why did I sell it?????) theres few mics that do everything as well as it does. And through a great pre this thing really gets a MOJO. How many mics do you know of that will do great kick drum,great electric guitar and sound perfect on ANY vocal?

I can only think of a couple and the other two are over 10K if you can even find one.

thanks for the words. i remember hearing people say that the 609 is thin and doesnt have give much body to a guitar cab. i'm sure its much cleaner and more articulate than an sm57, but body is important too.

what about the CAD equitek e100? how do those compare?

what i like about this style is the hang-it-over-the-cab approach (one less stand to worry about). from what i'm reading, it's much better to just put it on a stand - so what other mics are good for guitar in the $100-300 range? i like the body out of an SM57, but not the tone.

Sound like you need to experience a Kel HM-1.

Or maybe a ribbon.

I would agree the e609 and e906 mics don't have as much proximity effect as the Shures. But personally I don't want a mic that drastically colors the sound of my amp, which is why I don't like an SM57 as well as some other mic choices. I never understood why people spend their lives looking for the perfect guitar tone and then add a massive bass boost when they cram a mic with a bunch of proximity effect up against the grill. (bass that I'm probably going to roll of at the mixer 90% of the time anyway) Probably my favorite mics for live guitar amps would be the discontinued AKG D3600 and Sennheiser 441. If you've got a good sounding PA and a guitar amp with good tone, put either mic up and that's what you'll get at the board.

I understand the familiarity of the 57 sound, and I use that to my advantage if I'm micing someone else's rig. But for my own set-up, I want the tone of my amp to be translated to the FOH mix without any excessive added color.

Also when I'm playing live and micing a single 12" combo amp, rather than carry a mic stand I'd carry an 18" gooseneck and slip it under the strap handle on top. It gives you plenty of positioning options to get the tone you're looking for. The gooseneck angled under the handle easily puts you as far as the edge of the speaker, and it sure beats dragging around a mic stand.

i'd be using it in both live and studio situations, as well as outdoors sometimes. that kills the idea of a ribbon for me, unfortunately.