I'm generally not afraid to be out at night, have done it in a variety of settings (but always in moderate winds). Fitting lights to a DS is not that difficult.
(Look these up in my personal album for a description)
Being able to reef your DS is a must for any type of cruise, I'd say.
I don't have an outboard, only a trolling motor. For my type of sailing, that suits me (I have enough range to get to shore, even if I don't have enough range to go home in one go). 9hp seem overkill for a DS, probably even 4-5 would have plenty oomph. Agree, that it's a good alternative to being stuck out on the open water - however, if you get wind, I'd always plan to sail out of the weather in front of it rather than counting on motoring against.
I have a 40 mile trip I'd like to do sometime, but it's not crossing open water.
People who've crossed oceans in 16' boats had boats that were enclosed (more than a cuddy) and ballasted (keel). There was a Japanese sailor whose boat was/is? at display in San Francisco. 16' or close to it, if I remember. His biggest scare was when the storm punched out one of his windows.
I've sailed both DS I and DSII. Both are capable boats.