I'm worried that I will end up with a broken experience due to possessing many high-stage buildings that were never meant to be balanced with this mod.
Yes. I would not install CAM in a region that has been developed. It will screw up all balance.
You should use CAM from the start of a new region. It is a very good mod with lots of benefits. But don't put your existing region at risk.
I'm not talking about having a pre-existing region - I mean that I have hundreds of non-CAM buildings in my plugins folder, and I don't think it would function well with CAM.
CAM simply adds more growth stages to the game, so non-CAM buildings will function, however they may not grow at the same time as CAM modded buildings of similar size/occupancy.
The changes required to convert buildings to CAM are not that complicated, in-fact the PIM-X application (an alternate to the Maxis Lot Editor/Plugin Manager) can help you to easily adjust the values of your currently non-CAM buildings. Additionally a large number of buildings/lots have been made CAMPatible and are available for download which should help.
I wouldn't worry about balance. CAM 1.0 is fairly unbalanced itself because many buildings were "balanced" with an early version of PIM-X, leading to intriguing capacity numbers and such.
Even if that was not an issue, the Maxis building stages were not split apart so you'll encounter bizarre scenarios where (For example) stage 10 buildings are smaller than stage 9 buildings for the same lot size.
Fixing these issues would be something of a mammoth task, and certainly not worth it for someone who just wants to enjoy the game. Effectively, CAM is no worse nor better in regards to balance than the original game, so if you have no issue with the original game you'll have no issue with CAM.
tldr; Just enjoy the game. <_<