Makes some sense. When I get stats v2 up going I'll be sure to include share counts for orphaned blocks on the API side for this purpose.
Great! Post here when you do? In the meantime I'm using an estimate based on the ratio of block durations.
On the front end side, though, I definitely think the current method is more towards what someone wants to see as a "luck" stat.
For most miners, that's true. However on the odd occasion we have "Vladimir vs BTC Guild" style kerfuffles, you can show someone immediately how likely luck is over any given number of blocks. In fact having the current 'luck' side-by-side with the CDF might not be a bad idea?