I have worked pretty extensively with the 4000 model. *I have the stepdown version (if I may call it that!) the H3000. *
Honest to your god, it is pretty darn neato!...really though, the control over the algorithms just really stun me. *You can tweak away til you drop your left nut really! *
You can chain the effects, tweak the effects in the chain, and add parameters to the effects that are already in the chain.....and with a little time (when I got my first Eventide about 5 years ago) it took about a good couple of weeks averaging a few hours a night to learn the manual inside and out and understand what gets tweaked and how to go into those parameters via shortcuts and stuff. *It really is worth it though if you have the dough..it's multitalented! *
Not that I would discourage the GTR4000 but here are my two gripes against it.
1.) It's onboard pre-amp is not the greatest, yes, it is eventide, but their forte were the algorithms behind the effects not their pre-amps...the distortions especially are nice IF YOU LIKE industrial rock/metal...they are that 'metal-tinny' sounding...but the effects are the Eventide standard.
2.) Price wise, you are better off laying of the pre-amp portion and get a 3000 series. There is so much the 3000 series has right off of the bat off of the gtr4000. The gtr4000 has more spacial effects and time based effects geared towards guitar, but nothing you cant create based off of the algorithms given to you in the 3000 series..and if you REALLY REALLY wanted those algorithms, you can send the unit back to Eventide and have them install the EPROM chip with those sounds for a nominal charge.
I stand solid next to my Eventide NOT JUST for my guitar effects, but also for vocals, drums, keyboards...it is an extremely versatile piece of outboard gear which is worth experimenting with and owning if you got the cash.....the trick is to look for it EVERYWHERE, I have been VERY LUCKY in getting very good deals on the ones that I have bought. I paid under $$900.00!! for one in MINT condition....
www.harmonycentral.com is a good place and
www.digibid.com is another great place.
Oh and to add to your comment....the choruses, reverb, and flange are to die for on the eventide units...WOW!