Looking at the two inflatables: LSI-77 and -88, I notice that they have the same beam and tube diameter. The only difference is another foot of length, and a sturdier transom. The inflatable keel takes about 5 pump strokes to inflate, which is really minor.
In my experience, a dingy is a valuable addition to a cruiser, where you use it to explore, go ashore, and commute to other boats. If one uses it that way, please consider the advantages of another foot of "cabin" space. It will also allow you to use a 6 hp motor. I had a 4 hp Johnson and upgraded it to a 6 hp Johnson, and it made all the difference in the world, with regard to getting there.
I used to buy Avons, but now they're too expensive and I've switched to Achilles. Every bit as good as the Avon, but I miss the wooden unattached oars. Both are Hypalon, and that seems a bit sturdier to me. Also Hypalon is unaffected by sunlight, and the further south you go, the more important it becomes.
Boris