Hypothetically, I've figured it out. It had to do with one of my subcomps using an unnecessary "fire on start". This is the second issue I've solved by removing unnecessary "fire on start"s. Be careful with those everybody!
So, it looks like the crash was being caused by the chain of "add" nodes. The first was being triggered by the "fire on start" and then passing the event on to the next add block. I guess that was unnecessary, but for whatever reason it was making it crash. Anyway glad to have found the culprit.
So I just upgraded to pro and updated to the beta. I'm having issues with trying to run some of my compositions containing nodes I created on the previous version (as is to be expected). A lot of it seems to be connected to the new way subcompositions handle event flow. I'm trying to debug them and figure out what needs be changed, but Vuo keeps giving me the beachball of death when clicking the data ports of some nodes in the broken subcomps in question. Particularly while the comp is running. This is making it pretty tough to sort out what's going on.