I have been printing models for aligner cases and retainers in office for a little less than a year now. I print directly on the base since the very first day I got the printer, without supports, and never had an issue (all my stl files are prepared completely flat and hollowed in Meshmixer beforehand).
Surface finish is great, and fitting of aligners and Essix retainers is excellent. However printing flat without supports and hollowing the model gets me as fast as 50mins to 1.15hours just for printing, washing 15mins and curing 60 Celsius for 30mins. In total I need around two and a half hours to deliver a retainer if my assistant works really fast 
What I would love to know is wether Formlabs is working on alternate ways of SLAing to reduce the printing speed at least half of what it is now or even 1/3. That would really change the game in orthodontic appliances been delivered same day (especially retainers). I know you can not disclose future updates, but just wanted to note that regarding printing in the clinic, if you can speed it up you will make your many ortho and dental users a lot happier (because quality wise your prints are very good).
Just a happy Form2 user thinking about how I can improve my workflow in the near future.
Kind Regards,
Dimitris
Dr Dimitris Galaktopoulos DDS, MS