so this was due to elastic mode being on.
Allocation Pools are elastic in 5.1.1 and 5.1.0 by default, and memory reservations are NOT set on a per VM basis. The PDF i posted earlier pre-dates 5.1.0's release.
Allocation Pools are NOT elastic in 5.1.2 and anything 1.5.x and prior (not capable), and memory reservations should be set on a per VM basis.