For Rent - please help me decide

I got it on release and had no problems. But I mostly built and worked in CAS creating new households. Assigned rental units to just a couple lots, and moved in just a couple households. I have a feeling many simmers run into problems when switching those lot categories. Like switching from rental to plain residential before removing any unit specific traits and challenges. It seems like the game should give a few warnings before switching category, it should not be possible if it causes problems...

I believe you will be safe if you just move households into units, and the leave them there. But probably even safer if you wait ;)