I have been diving from a 15' Avon inflatable with a 40hp Tohatsu 2 stroke for about 10 years in Southern California. It's a fantastic boat. I have it set up with a tiller steer for maximum deck space and I mounted a GPS/fishfinder and a VHF radio on stainless steel brackets bolted to the transom. I have taken the boat to Catalina (26+ mile crossing), the Northern Channel Islands, the North Coast, Lake Powell etc. and it's handled everything. In flat water it will cruise at 25 mph (feels like 125 mph!) and I average about 4 miles to the gallon (12 gallon tank).
The boat can handle three divers with six tanks but it's a squeeze. A couple of divers is much more comfortable and manageable
Since you have a lot of experience with inflatables, it's probably not news to you that you really have to pick your day. If there's any kind of wind over 5-10 mph, it will get miserable pretty quickly. Wind chop will make you feel like your fillings are being hammered out of your teeth. You really have to slow down to handle rougher seas but the boat has tons of flotation so it's a comfort more than a safety issue. The boat can handle a serious beating but you'll quit before the boat does.
Also, the wind will take the bow spray and throw it back at you so be prepared to get wet. I always keep my wetsuit on and carry a boat parka so I can wrap up and stay relatively warm, if not dry.
As for getting into the boat, I always clip off my gear and belt in the water and kick over the tubes. It's easier once you get the hang of it but weight/strength ratio is a factor. A ladder looks like a nice convenience but every inch of space is at a premium and even a small ladder will likely get in the way. You have to weigh the trade off -- of course, if you need it, you need it and you make room.
I carry a 4kg anchor with about 15' of chain and 200 feet of rope stored in a milk crate with a plywood lid (it doubles as a bench when the anchor is stowed). Anything you can carry that does double (or triple) duty is appreciated on a small boat!
In the long run, I decided to trade up to a 20' cuddy cabin for comfort. I still enjoy the "bare bones" feel of the inflatable -- a Jeep for the ocean as it were -- but some of my buddies complain about the rough wet ride and their sore backs. When I want to take a couple of buddies out or if I want to do an overnighter, I take the big boat but for now at least I am keeping the inflatable for economical "hit-and-run" local trips by myself or with just one buddy.