For some incomprehensible reason, in the early 80s, Alembic sent pickups and perhaps electronics to Aria Pro to build their Alembic copy RS850 (the 750 had passive electronics, the 850 had 18v electronics). The specs are identical to the Alembics of the time: two single coils with a dummy coil for hum bucking, neckthru design, 6 on a side tuners, 18v electronics with proper low pass filters with 3 positions for each and hardware that seemed to be a copy of the Alembic stuff. Not sure why they decided to help Matsumoku out, but there it is.
The main difference between the guitars was that the Aria had the wings for the neck thru design made of solid walnut or other wood, whereas Alembic had the wings veneered top and bottom with highly figured woods for a more deluxe appearance. The inlays were very similar. The Rev Sound had a painted on logo vs the Alembic metal badge.
I just got an RS850 in really nice shape and I'm definitely enjoying it. I"m waiting on an Alembic for a straight AB comparison, but from my 10 year old memories it sounds the same. Very cool tones from straty*jangle to smooth jazz with stops for hard rock in between. Some have complained that the Alembic pickups sound sterile and cold, but I think I could live with them. The only problem is learning how the 3 position low pass filters sound in various combinations and positions. BTW, the thing KILLS with distortion. Doesn't seem to matter what pedal but either the Klon or the Honeybeest into the CAL Holy Fire is a wonderful sound, with moving the LPFs giving almost a wah feeling to the whole thing. Worth finding (the RS850s seem to sell in the $1200-1500 range vs the Alembic $2k to $10k depending on how deluxe and how old).