Just a heads up, everything is working pretty good with 3ds Max 2013, FPro 4.0.2 and Maxwell 2.7.2
In fact, my HQ Plants work well, and MOST of the presets that come with FPro work well (except the billboards, because Maxwell doesn't read bitmaps). However, the grass does not work (none of the presets, nor the standalone 3D models). I believe the issue is the grass used a double sided material, which Maxwell does not recognize. Additionally, there is a "normal bump" used, which again, Maxwell does not recognize. If everything is kept standard, it seems to work (like I said, all the trees and everything else seems to work fine).