I can't seem to find anyone else that has done this and written about it. But, I may not be looking hard enough. Here's my experience. 1) Turned on iCloud photos beta for Mac 2) Took about 4-5 days to upload 20k library (120 gigs) - Totally fine in my opinion 3) Sync was going great for a while between iPhone and Mac 4) Something happened so that I always had "31 photos uploading" 5) Tried pausing and resuming the service. 6) Turned off iCloud Photo Beta on Mac 7) Turned it back on 8) It said "adding 20000 photos" which took about 20 minutes 9) It warned me that it would use the rest of my 200GB limit 10) It started uploading the same library again Any experiences similar to this? I was hoping it would just see that it was the same set of photos and not actually re-upload them... fixing the 31 photos syncing issue. Don't think it's totally ready for prime time, but my experience other than that has been pretty solid. **I can't turn it back on, however, because I don't want to sync my 20k photos again.