Ok, here's my report after spending some time getting to know my way around the 350. I'm repeating this from my posting on the craigslist/ebay forum.
This is an unreal vintage guitar. It's probably as close to "off the shelf" as you're likely to get on a 50-year old guitar. It's positively stunning. The gold plating is still full of depth and shine, even on the harp tail piece. No dings, no mars, no nothing. As described in the listing, the push button switch plate has a broken screw hole on the side closest to the tone knob. It looks like a victim of shrinkage. The broken piece was effectively glued back on the plate, but the hole no longer lines up; hence, there was no screw in it. The TM (treble middle) knob has been replaced by an unmarked (plain), but perfectly matched, knob. Other than that, it's a real time machine. No noticeable player wear on the original frets. Beautiful guitar.
After playing for almost two hours, I'm getting familiar with the tones that come from the various pickup combinations. The switching system allows all combinations of pickups, but the middle and neck pickup positions have two different capacitors in place that mute the tone, with the neck pickup being the darkest. Selecting the neck pickup alone on this guitar reminds me of flipping the "mud switch" on my Country Gent and Tennessean. It strangles all the treble leaving a preponderance of low frequency mud. A completely useless tone on the Gretsches that no one used. Unless you were covering while the bass player grabbed a beer.
I've read suggestions on LTG that suggest disabling those caps will provide a straightforward selection of pickups without cutting the high frequencies. That's how I was expecting them to be, so what I have is something of a surprise. Before I go monkeying around with anything I want to hear more about what Guild was thinking. They produced this guitar for a good number of years, so it must have served someone's purpose(s). I can only wonder.
The single volume and tone control make this an easy guitar to fiddle with during play, much like a two-knob Tele. Pushing buttons will never be as fast as flipping switches on the fly, but it's really not that difficult, especially when seated. I have a three-pickup H-78 Harmony that I love, but it has three toggle switches, one for each pickup. Changing pickup configurations on that can get very flippy very fast. You have to remember where you are to know how to get where you want to go. Again, you get used to anything.
So, bottomline for night #1, gorgeous guitar, incredible shape, strange tone shaping, but a fine playing instrument.
I'm still eager to hear from those who have modified the 350 tone circuit or have found contentment with it the way it was designed. If it's working for you, how dod you have it set up, and for what kind of music?
Thanks to all...
Bill