FF-
The 23 Reg is one of my favorites too. I was showing that rig just for the performance comparison. There are a few distinct advantages to a single engine--initial cost, weight, performance, fuel economy, maintenance, parts and labor. For offshore, twins are a safety factor. The reliability of Yammy four strokes negates some of that need. This is particularly true on a 23' boat. There are some who may run 80 miles out in a 23 but not so many.
For the fishing I do, I dislike two engines. I often fish tight to structure, fish racing albies, move rapidly to breaking fish, etc. A bud has a 32 Seacraft with twin 250 E-tecs. It is a wonderful boat for running the ocean but he has it in the bay, and the two engines are cumbersome.