I ended up buying a PGMM31 Paul Gilbert Mikro of my own and I wanted to update this thread and share my experience with it.
Out of the box, I would rate this guitar at something like 3.5/10. It came with 0.010 gauge strings and had pretty poor tuners, and it was nearly impossible to get the thing tuned in the first place. Then the strings were too floppy for any chords to be in tune and correctly intonated. I stretched the strings like crazy and it somehow still had trouble just getting to and holding standard pitch. Pretty frustrating, and just no fun at all. I ordered some higher-gauge strings and additional upgraded parts, and I kept it tuned up a half step (or maybe a whole step, I can’t remember) while I waited for the new strings to be shipped; this made it barely tolerable to try to play. The pickups had decent output but sounded thin and harsh to me. Passable, but not inspiring. The action was high and the saddle height adjustment screws were poking out from the saddles and felt sharp and grating and interfered with palm muting and my normal hand position. The strings made creaking and cracking sounds when tuning, indicating binding in the nut/string trees. The frets are good, though; smooth and silky, with no protrusions at the edges.
It took a lot of work to get this guitar playing well and sounding good, but I think it was worth it. Now it’s at least an 8/10 for me; it’s a blast to play, sounds more than decent after pickup swaps, doesn’t feel gimmicky or cheap, and it’s the perfect little shredding machine that I was looking for. I first tried 0.011 gauge strings, but they felt too stiff for me (I’m used to a 9-46 “super light top/regular bottom” set on a 25.5” scale), and I ended up with a D’Addario “10 plus” set, which is 0.0105-0.048 (or "10.5-48"). With the short scale length this feels very similar to the 9-46 set that I’m used to, and chording is stable and not floppy, but some of the big easy bending is still possible.
My main guitar is a Kiesel DC727 7-string with a fairly substantial neck width and thickness, but the PGMM doesn’t feel too small or cramped for me (and my smallish hands). It feels pretty natural when I play it, and after just a minute or two I forget that it’s a shorter scale.
Here’s a summary of the modifications and improvements that I performed:
Strings (replaced 10-46 with “10 plus” set, 10.5-48)
Pickups (replaced with a DiMarzio Crunch Lab in the bridge and a Stewart-MacDonald Golden Age in the neck)
Tuners (replaced with Kiesel locking tuners. I initially wanted green Sperzels to match the Crunch Lab, but they only have a 12:1 ratio; I opted for the 19:1 Kiesels instead)
String trees (replaced with Graph Tech Tusq string trees)
Nut (sanded to reduce height and increase string slot widths)
Truss rod (adjusted to reduce excessive relief)
Saddle height adjustment screws (removed and cut down to reduce length so they no longer protrude above the saddles)
Pickup selector switch
I usually prefer a 3-way switch and DPDT toggles for coil-splitting, but in order to keep all of the controls inside the f-hole pattern I replaced the original pickup selector switch with a 5-way “superswitch” to allow for the following combinations:
Neck humbucker
Neck single
Both single
Bridge single
Bridge humbucker
In the single coil positions a 470k resistor is added in parallel with the guitar’s 500k volume pot, which creates an equivalent maximum pot resistance of ~250k which is typical of single coil guitars. This lowers the resonant frequency and keeps the upper mids and treble from being too bright or harsh in the single coil configurations.
I replaced the no-name linear volume pot with a 500k audio taper Alpha.
The electronics cavity originally only had what looked like a single swipe of conductive paint down the middle, so I installed copper foil tape over the whole thing (and in the pickup cavities).
I also installed a treble-bleed circuit (0.001 µF in series with 150k).
Since there’s no tone pot on this guitar I added a 470k resistor in series with a 0.022 µF cap to ground to replicate a standard tone pot on 10.
After all of this work this guitar is very enjoyable and even inspiring to play. I’m having a lot of fun just chunking palm mutes and shredding Van Halen and hair metal and working on speedy stuff. I’ve always liked the look of the PG signature model and I appreciate the humor of the painted-on f-holes. The small size and bright green humbucker add to the novelty for me and make this a really fun and unique guitar.
If you have the time and inclination to perform the necessary upgrades (or are willing to pay someone to do them for you), this has the potential to be a very playable, very enjoyable guitar.
Thanks again to
@Sustainerplayer for the initial post.