So, I've played another 4 hours this morning. Started a couple games, and have been getting unstable around turn 150-200 in general.
Crashes seem to be occurring between turns when there is a ZoC calculation, or after I've re-grouped military units in overland (could just be ZoC coincidence, though). There also seem to be some save-related instabilities yet also, as I've crashed more than once while saving.
The odd thing that I've had happen twice now is after a CTD, when I try to load the game is the opening screen pops up, then I get a dialog box that says "failed to download data file. Make sure you are connected to the internet.." and other such. Impulse says I'm at most recent patch.
The oddest thing is that particular error happened 2-3 times in succession, then went away for no apparent reason, and I just had it again 2 times in succession.