Re: are there any actual stats on chain reorgs, by depth?

It seems 10 blocks at current hashrate would be very rare

Extremely! This is closely related to the odds of pulling off a double-spend 10 blocks deep. D&T explained nicedly at https://bitcoin.stackexchange.com/questions/1170/why-is-6-the-number-of-confirms-that-is-considered-secure.

The worst was the overflow bug. That would have been around 53. https://en.bitcoin.it/wiki/Value_overflow_incident

My node only goes back to 2012, so I missed out on the overflow fork. But I have the next big one. My node saw the .7/.8 fork at a reorg of 30:

Code:

{
"height": 225459,
"hash": "000000000000036e459f26b1dc02683c9beeb061eedf18689995143354467245",
"branchlen": 30,
"status": "valid-headers"
},

Feel free to analyze my data at http://pastebin.com/LZxst5vD.