I have moved from Photos to the new Lightroom CC (but haven't deleted my Photos Library, still hedging my bets)
I have 75,000 photos/500GB in my LRCC Library and it works brilliantly. We have two computers and three iDevices syncing to the Adobe Cloud. In many ways it is
better that Photos.
(EG1: Unlike Photos, LRCC syncs referenced masters to its Cloud, and the referenced masters can be on an external drive.
EG2 : You can chose which albums are stored locally on your devices to avoid the tedious delay to download which sometimes occurs with Photos)
For many years my wife and I used the same Apple ID, which meant all our photos were automatically combined into a single library and all edits sync'd....wonderful! Then she got an Apple Watch, which effectively forced her to have her own Apple ID, so we no longer had a combined Library. Tried Family sharing (low res only) and manual exporting/importing (ugh).
IMHO the main drawback is that it will cost you $10 per month for 1TB. In my case I will be able to recoup some of this by dropping down from the Apple 2TB tier in iCloud. Also at the moment there is no printing out of LRCC, but there are ways round this. Photos printing options are better. LRCC is a work in progress with significant improvements coming regularly.