The information is just how close the drivers to your ears. AD2000 have softer pads and tighter clamp, while the AD1000PRM have firmer pads and lighter clamp. Hearing a stock AD2000, along with a pad + clamp modded recabled AD2000 and my AD1000PRM. I can say the modded one sounds the same as my PRM while the stock AD2k is bassier and true to reviews.
What is the conclusion? Modding them will give you the same as importing a pair of PRM and mods are reversible!
I once read that they actually have the same drivers and it did seem like there may have been a difference in clamping force. The AD1000PRM from the descriptions actually sounds to me like a true successor to the AD900 (whereas the AD2000 goes off to a completely different direction).
It's nice to know that it would be perhaps possible to get an AD1000PRM in the future if I ever miss my AD2000, and maybe do some pad rolling. Shure 840 pads might be interesting!