Swinging moorings probably the cheapest way to keep your boat on the water but comes with risks ie I am glad my boat wasn't on swinging mooring today! Another downside is security but then we all leave our boats in exposed places so no more risk there than anywhere else. A dingy maybe needed to get to your boat unless your mooring provider has dinghies for use by customers. If you have to supply your own dingy then that needs to be kept somewhere.
Parkstone Bay is a well run yard and I am sure you will be fine there. I would think their moorings are likely to be well maintained however I have no experience with them, do ask questions on that point indeed if you consider anywhere else ask the same questions. Parkstone bay run water taxis for mooring holders but not sure of timings or if this is seasonal again ask the questions
One of our members works there he may well be along in a mo to give you the low down
Martin