Thru the years we have owned a number of inflatables. There is no substitute for a real dinghy--a paddle board or even a kayak cannot do the same things--despite each of these being excellent for what they are intended for. The dinghy is you station waggon, touring car and life boat.
We currently have several inflatables, including the 6'6" wooden transom, slat floor, West Marine (Zodiac), and a 9'6" inflatable floor. We also owned an 8' wooden transom slat floor (Zodiac). My experiences early on with the round inflatables, and un-reinforced (slat type of inflatable floor) was that they were unstable when you got in the boat--and we have avoided them for years. The Alaskian boats are very well made--and may be an exception to this. We used both the 8' and 6'6" inflatables on our CD 22, and I believe that either would have been OK with a low arch. We kept the 6'6" boat and used it exclusively this summer in the PNW--it is tight, but do-able with one 200 lber and one 120 lber aboard....plus a small dog, but the 8' boat has a lot more room. Remember than a 6'6" boat will only have about 4 feet of usable length in the actual hull (18" overhand aft, and 12" tube foreward--the 8 boot boat increases this to 5.5 feet inside of the boat. A 9'6" boat gives you almost 8 feet inside of the boat. Also consider how fast you want the dinghy to go--none of the boats you are considering will plane--and most likely you will row (a bit of frustration if going any distance) or a 3 hp engine. If you want to plane, you need to have a inflatable floor, and at least 6 hp--better 8 hp.