As long as you don't need the dinghy to go too far, like taking you out to dive/snorkel
reefs or
anchoring a couple miles away from town, then I think you would be fine with either the ultralite or rollup with the torqueedo. At that point, it's more of a preference for the other features/benefits, ie. solid floor, sturdy bottom for pulling up onto rocky beaches, roll-up
storage convenience, etc.
Your davit arch will make using the ultralite
rib pretty convenient, and reduce how much you need to store the dinghy on your
deck.
I have a Highfield CL310, which obviously is heavier than the ultralite, but my epropulsion spirit is great for when I'm in a
mooring field or anchorage to take my dog ashore, or popping to the town
dock to go
shopping, or just poking around to get a look at other boats. I don't think that you'll ever get the torqueedo to put you on plane, even if you have the flat bottom rollup, and with my epropulsion I found that I liked to run it around 60% output to optimize
battery life and still have decent speed. The
battery does take a while to charge from my housebank, I'm tempted to get a second battery, but they are pretty expensive.
All that being said, I'm really glad that I also have a 20hp gas
outboard for when I want to explore or
anchor further from town. But I definitely don't regret getting the epropulsion either.