tl;dr: 74.32 is playable. Just don't overbuild and *especially* don't build too many lights. Keep shadows disabled. Even then, I'm getting crashes averaging probably 1 every 2 or 3 hours. Still, I'm having a blast

My gaming rig is a new build: i7 quad core, 980 ti GPU and 16 GB RAM. Game installed on a 1 GB SSD. Running Win 7.1 64 bit. Playing the game in 32-bit mode using the DX9 API's.
So...your mileage may vary.
I've got 100+ hours into my 74.32 playthrough, and it's very playable...at least for me. There are some issues, especially as you increase your number of squads and "serfs" and the complexity of your properties. I retired recently, and have the time to play for extended sessions (sometimes 8 or 10 hours a day).
The biggest issues revolve around your NPC's becoming non-responsive to orders. I currently have 26 of the 30 allowed. (2) 8-man fighting squads, (1) 4-man armor and crafting squad, and just started my 6-man agriculture squad. I have a main outpost with stone and ore mining, 2 buildings owned in Trader's Edge, and a new farming outpost.
At least once an hour, I have to save and re-load to debug stuck squad members. Some of the more complicated and automated NPC tasks are simply too laggy to use (such as corpse retrieval and incineration). This is to be expected with alpha code, of course. Strangely, lights seem to be a main source of the problem. Install too many lights and things in ALL your outposts get majorly bugged out. Clicking to move any of your characters means you give them an order...and then wait...and wait. Eventually, you restart the game or import the save. I tried to build an Outpost IV building at the agriculture outpost...and it basically froze up my entire operation throughout the game. Probably because I went overboard on lighting.