One more perspective on the mirrorfree revolution.
|2.5 kilos vs 1 kilo|
BTW, with Photoshop CS5's Quick Selection tool (by the Magic Wand), one can often make a good enough selection quite quickly, and then blur the background to heart's content. Example:
I messed up the selecting by her knee, but this was a very rough-and-ready job, took a minute or two even being not familiar with the tools.
In other words, if you only need very soft backgrounds occasionally, this is not even a reason to use full frame.