They each have their own advantages. P600 is fast, well respected and can have large cartridges. P600 is one of the most well-known platforms for DTG/DTF and is a popular choice.
Our P600 DTF machines have an external tube for waste ink, no waste tank. Cartridges are large. 80ML
Yes, white ink must be regularly circulated. On P600, Cartridges, dampers and tubes will have ink in it. All will need to have ink circulated. Fairly easy, but some ink loss.