Here is quick update on my 12mm rod upgrade. The 12mm rods are installed and I've been printing on them for a few days. They work and the platform seems more steady while printing. There is definitely less side to side movement. I haven't noticed a huge increase in print quality, the quality wasn't that bad to start with and it is still pretty good. I tried to do a before and after test print but it looks about the same, not sure If my test print was the right structure to see a different.
So was the upgrade worth it? I only spent about $45 on the upgrade. It was kind of a pain to disassemble the entire machine (I had to do it about 3 times to get the adapter parts designed right). It was kind of fun to do so yes I think it was worth it, at least for me. I'll try to get the parts posted to Thingiverse in the next week or so, maybe somebody else can do it and figure out better test structures to test before and after.
Here are some pictures:
Bearing adapters (Also designed a new shim for 1/8" glass to fit the new bearings)
Attachment 9151
Bottom adapter
Attachment 9152
Top adapter
Attachment 9153