Well yes Atlantis use 1 million dollars mill to do their abutment at their quality.
Second, milling abutment is really a bad idea if you don't use a proper machine but heh if you want to deliver bad solutions and product to your doc, your choice!
Milling ZIRCONIA is another questions, a nice small machine can do a lots in zirconia since precision is not a requirement with Zirconia, you will always use a TI base on implant or cement between your final crown and your abutment or bridge.
Milling TITANIUM is an ART and trust me, few know how to master it, many try and believe tho! You can go in school and take a 3 to 5 years class in college to learn how to run a 5 axis CNC and you believe that a dental tech lab could learn that on a forum on internet? No you can't, same as learning dental technique on internet, you can't, you have to take class and even the top tier dental tech in the industry continue to take class to stay on top
Not different in milling world!
I still think that a lab should get a nice Zirconia mill and outsource the titanium and Co-Cr to industrial manufacturer.
Oh and we didn't even discuss about spindle that break! $$$$$$ even on a low cost machine, sometime it cheaper to get a new mill than replacing the spindle!
So to answer the OP question, a nice Roland is really an awesome choice to start, easy to get a 2nd in case your machine have a problem and not stop your production.
My 2 cents