I have used both types of grills (technically, they're not Bar-be-ques), charcoal and propane and I much prefer the taste of grilled food when cooked over charcoal. However, charcoal is considered a hazardous cargo when carried aboard a vessel as if it gets wet and begins to dry it can be subject to spontaneous combustion. When we were using charcoal, we would decant it into double zip-lock bags, which seemed to work well.
The propane grill is easier to light and quicker to get hot but adds a fair amount of complication. The Magma propane grill that we purchased a few years ago is now completely worn out and even though Magma maintains an extensive inventory of spare parts
(God bless them!), I don't think it's cost effective to overhaul
it. Regardless, our new one will be the same model.
Fair winds and calm seas.