The drive and amp settings are the same throughout - only changing tones with the volume and tone knobs and coil splits. There are some delays and reverbs in there, but the drive tone is all controlled via the guitar.
Backstory: I've had my ESP Eclipse about 10 years now, and along the way I switched from the stock EMG 81/60 combo to a DiMarzio Dominion and Liquifire, and then a JB. I was completely new to wiring/soldering and it didn't look pretty, but I used the correct pots and everything worked fine. Anyway, I decided that I enjoyed the coil splitting function on my new Charvel so much that I'd take my Eclipse in to have it professionally rewired with a coil split added. I thought it would be nice to have a professional do a clean wiring job and have everything look nice. I found a local luthier with 5 star reviews and a shop and told him everything I just told you. I originally asked for a push pull master volume split, but after waiting over a month and him insisting that it was "too hard to get parts these days" and that he couldn't get a push/pull pot in stock, I agreed to a mini toggle switch that was available. Well, it ended up being a nightmare and the guy did a terrible job. I knew something was up when I heard tons of noise from the neck pickup and noticed that the coil split wasn't even affecting the bridge. When I talked to him about it he insisted that it was "the only way it could be done", and had several other reasons why it was everyones' fault but his. I got it home and opened it up to find this:
Notice the red and white wires from the bridge aren't even connected to the DPDT switch. I'm no expert, but I feel like if the coil split switch isn't affecting the bridge that might be a factor?
Well, rather than take it back to him I said screw it, I'm going to get exactly the parts I want, practice soldering, and do this right. I picked up a '59 neck pickup to really make it match my Charvel, a DiMarzio 500k push/pull pot (which arrived in two days from Amazon, so apparently it is possible to buy parts, whatdya know), and studied up before getting down to business.
This is the end result. It's far from flawless, but I feel like it's decent for a newb with a $15 soldering iron
Master volume push/pull coil split, master tone, and an un-wired third pot to fill the gap as I just wanted a two knob setup like my Charvel without hurting the looks of the Eclipse. I did a common ground at the top of the DPDT box after finding the general consensus was that this was a good spot according to other gear nuts. After play testing, everything works perfectly and there's no more excess noise, so I'm a happy camper!
Now like you said, what to take apart next...