Yes interesting, but accurate at least for me.
"All things being equal", there is more RAM used on my HP Compaq OS when ASB is used as opposed to when FF (Sandboxed) is used.
NOTE:
"All things being Equal"
Screenshots:
As shown, the amount (%) of RAM used on OS with ASB is 42%
The amount of RAM (%) use when FF (sandboxed) is used is 35%
The RAM does decrease (slightly) on idle with both Browsers, however ASB always shows more OS RAM used