So I did another backup, getting the version to 2.0.122. Restored data on my N5 which prompted a reboot due to updating system data.
Upon reboot, all my SMS are now present in Hangouts! Even my "group" SMS. Not really keen on restoring system info to be honest due to possible issues, but it seemed to work. MMS, however aren't really working well... I see three bouncing dots for every picture.
This time I tried to do what someone in the other post said. I backed up Hangouts, uninstalled hangouts, and tried to restore the app only. Unfortunately this led to a Titanium Backup hang. Upon forced restart, the Hangout app is back, but all the SMS/MMS are gone. Re-uninstalling and re-installing Hangouts with data this time and also getting another hang in Tibu... this is highly annoying. I guess I can always just get the SMS and save the pics on my other phone.
Nexus 5 32GB Black: Rooted, Stock, Stock Kernel, TWRP
Samsung Captivate w/ (insert ROM of the day)
Kernel: ROM Stock Kernel
Graveyard (but still functional)
Samsung Blackjack II