Thought I'd chime in on the Q-Tron/Mutron posts. Also, thanks to Tennessee Jedi for the kind words about my guitar tone...
Although lately I'm not using any effects I do have an extensive Jerry rig that I use for work I do with my band, The JFP, and different Dead cover bands that I sit in with from time to time. I have an original Mutron III from the mid 70's, with it's original power supply. I've used a Q-Tron as well some time back while I was overhauling the Mutron III. I found the Q-Tron to be pretty convincing but because I work on gear for a living I know that the components in the Q-Tron are computer grade stuff. I am a true beliver in using higher grade passive components such as capacitors, resistors, pots, etc. Even transistors and IC op-amps come in so many flavors and construction quality. Unfortunately Electro Harmonix is not of the same mind anymore. EH/New Sensor in general has turned into a budget effects company and the quality of their build is suspect from unit to unit. I was however able to dial in a very convincing Envelope with it, I just never felt the quality was high enough for my standards.
As far as the Unity Gain Buffer, I built my own for one of my guitars and found that I just didn't need it. If I was using the Mutron for a tune like Estimated I would set the Gain/Threshold to a nice balance and when the lead break came around I just picked a little harder to get the envelope to open more. This gives the effect of having a little more volume on the older of the Mutron III's. Picking dynamics are key in getting the Mutron III or Q-Tron, or any envelope follower to work for you. It's super frequency selective as well so that's exactly why you get different dynamics say on the high E above the 12th fret versus the lower notes as in the Shakedown vamp. I like the idea that Jerry came up with I just felt it didn't work for me, as in it wasn't really necessary. I do however have custom built pre-amps by Alembic in all my guitars similar to the Stratoblaster. Mine have adjustable gain trimpots which can bring me down to unity (0db). I keep em' all adjusted a little hot which gives my amplifier pre-amp a little kick in the ass. Not distortion, mind you, but a little hotter tube tone on the front end.
As for my main rig with or without the Mutron III, I have a heavily modified Mesa Boogie Mark I Re-Issue. It's my main gig rig and does just about everything I need it to do. I did the work myself over a period of time looking to match Garcia's tone from 75'-76'. A tweak here and a tweak there. Or I'd gather up some new info, or a supposed modification he had done, be it rumour or not, and give it a test drive with my own stuff. Either thoroughly debunking it or in the best of situations, getting closer to what I think is a close match. It seems to work nicely and my older modified 70' Twin Reverb is collecting dust these days. I do frequently use a seperate power amp to drive the Mesa Boogie. It's a beautiful old Electro Voice 7300, 600w(300 & 300) stereo amp. The closest commercial production amp you can get to a McIntosh 2300. I don't always use it though. I just don't need that power. The Mesa has a very clean 100 watts.
Speakers really play a big part in making your envelope bear fruit, so to speak. Speakers these days are all JBL's. I'm fond of the 2204H. It's a real sleeper from the JBL line. Most cats wouldn't think to load a guitar rig with it but give it a shot. It's got the rolled off highs built into it's frequency range. Really thickens up the lead tones, particularly on a Strat or single coil guitar. The Mesa has one in it. I have a 2x12 extension cab w/ K120's but again, who really needs that much?