I have two Dolphin Diagnostics at rent houses and a Premier at my house. If you are buying the Premier just because your current unit's bag clogs too quickly, you will be very disappointed with the Premier. It works great, but I can get three times as much in the older bag models. And... it takes me twice as long to clean the cartridge-like filters as it does the bag version. You can throw the bag in the washer, something you can't do with the cartridge filters. My Premier came with three filters.. Screen, pleated filters, and a bag.
The bag is not like the older Diagnostic's heavy bag. It is thin cheap POS. It will pick up leaves and stuff but does not really filter anything. The Screens pick up stuff, but leaves any dust/fine dirt behind, but they don't pick up much at one time. The pleated filters do a great job of picking up any dust/fine dirt, but are a real pain to clean.
I love the way the Premier runs, but I really wish it had the same heavy bag system the original Dolphins had.
YMMV.. Jim R.