I ran across a cannibalized Segway MAX a couple of weeks ago in a dumpster: no box on top, no battery, no controller, and all the wires and connectors were trashed. Basically a frame with wheels.
Yay! Project scooter!
Since all the guts were missing, I took apart my M365 and installed the battery, controller, and dash board; I spliced all the wires with a pile of WAGO connectors I had handy and to my surprise, it works perfectly!
But with the stock M365 board, it felt a little pokey. I had a PRO board that I'd been meaning to install, so I dropped it in, flashed it, and it's much better.
Next step: I plan to install a second M365 battery pack in parallel -- there's enough room in the bottom of the MAX to hold two M365 batteries on-end.
As far as the user experience goes, the MAX feels like a beefed-up M365. I've always preferred the M365 over the ES2-4s. The ES models always felt a little rickety to me, and I hated the clack-CLACK whenever I'd hit a bump. The MAX compares favorably to the Bird One in terms of ride feel. The larger wheels make a huge difference on rough pavement and when going from the street-to-sidewalk. The small wheels on previous scooters would tend to tramline if you went from the street to the sidewalk at much less than a 90° angle --i.e., the front wheel might make the transition but the rear would want to ride the line of the driveway apron and as often as not result in a spill. But the larger wheels make the transition much more smoothly and safely.
Still, I'm looking forward to a proper conversion solution and hoping someone smarter than me figures it out and shares the info. I'm watching the local auctions to find an intact MAX!