I think it is important to stress that sensible is in the eye's of the beholder. We all have different ideas of sensible based on our perception of what makes us comfortable. Don't change your perception of what you consider comfortable to conform to other peoples opinions of what is "sensible" to have on your boat. You can always expect someone to criticize but what the heck as long as you are comfortable and have what you want (not just what you may need) at anchor or in a marina you are good to go.
I have redundent GPS/chartplotter systems, several VHFs, Radar, laptop with PDA backup, air conditioning, refrigeration/icemaker, generator, invertors, dinghy, inflatable, outboard, bow thruster, the kitchen sink, and a huge pilothouse with side deck and back deck doors. When I go places I am comfortable and if something fails (except that trusty perkins, knock on wood) I can continue my trip while a new part meets me at a future port of call. I can sail or motor and regardless the weatherand and I am comfortable.
I would suggest that the primary guide to use in outfitting for cruising is your perception of what "you" need to be/feel comfortable because being sensible (having, using, or showing good sense or sound judgment) implies that you would not undertake a lifestyle where you were not comfortable right. Take ideas from forum posts but let your comfort level temper the ideas to your level of "sensible".
Boating isn't an attitude it is a way of life