Gut says it's too small. Without a helmet, my head fits inside the crack....but that's all I know for comparison. I have a new #6, but not sure I ever carried it up there to try.
It will protect with small aliens (blue, black, blue/black) in the small horizontal crack inside.. I suspect other small gear works as well (new small tricams for example). The problem w/ the small gear is that you pretty much have to place by feel, plus vigorous pull-testing. Never fell there, but I suspect the couple of pieces placed were good.