I've been messing with midi guitar since the 80s, when I had a Roland 707 system. I've used various Roland models since then. I have used various pickup systems in that time frame as well.
The Roland stuff has gotten better over the years, but the best from my experience is the Axon AX-100. It uses neural nets to determine the pitch MUCH faster than Roland can. Yamaha also licenced this technology to use in their midi guitar product. (see
http://www.yamaha.com/yamahavgn/CDA/Con ... CT,00.html)
Blue Chip, the original manufacturers, have sold rights to TerraTec (see:
http://messe.harmony-central.com/Musikm ... -MkII.html)
I can tell you that the configuration of the device is not for those who fear technology, but that has it's rewards ... as the capability of the device will allow you a lot of creative flexibility. Things like separate patches for each string, and patches that can change based upon where you are picking, or playing, etc. The Blue Chip version that I have doesn't allow configuration thru computer, but I understand that the TerraTec units feature a USB interface for that purpose.
If your instrument is setup and intonated properly, you'll have better results. Also, calibrating the system to your playing style helps also. That said, there is no better suggestion I can make than to work on your technique. Pitch to midi conversion and sloppy playing are not a good mix. The last suggestion would be to work on playing the sounds, not the guitar. If you simply play midi guitar with riffs that you would play without it, you won't necessarily be pleased with the results. You need to step into the mind of the instrument's voice, and play that.
My current rig includes a one-off guitar that I built with RMC piezo pickups on a Warmouth Strat body with Fender 57 reissue neck. I also have a PRS CE Soapbar II with the Roland GK 3 pickup on it, which I now use the most. These run thru the Axon AX 100 out to E-Mu Planet Earth, E-Mu Proteus 2500 and Arturia Minimoog V (soft synth on Mac). I am anxiously awaiting my Voyager Rack Mount Edition to eliminate the need for the computer.
FYI, everything up to this point has been in search of the Holy Grail of synthesis, and with Arturia's Minimoog V soft synth, I found THAT SOUND. Fortunately, it allowed me to test my rig without spending $2k on the Moog, unfortunately, now I'm spending the $2k on the Moog.
I hope this helps you. If I can be of further assistance, please contact me. I'm not a reseller or invester in Moog or other products mentions, so my opinion is my own ... but I'll share what I've learned.
-jm