Thank you, DIY options are attractive because of price, and it's impressive there are even 6DoF projects, but many seem to lack the repeatability I am after (or their repeatability isn't clearly stated). If you have personal experience with one, I would be interested to hear about it.
Depending on how much you are comfortable tinkering with control electronics and encoders, know that getting a good repeatability can just be a matter of tinkering with the control eletcronics: