keep coming back to see what's been posted ... as this is one boat I really would love to ultimately settle into ...
I have belonged to the Gemini Group for years. I have found them to be honest and straight forward about the boats capabilities; reality based. The design of the hulls and various features have undergone changes since its inception just as you would find with any sailboat who's popularity has maintained its production; I believe more Gemini's have been built and sold than any other multihull. The designer and his son sailed the 105MC to Europe. Prior to the 105MC model the designer specifically stated the boat was not meant for open blue water sailing such as for RTW. There are 105MC's circumnavigating worldwide.
Regarding motorsailing and multihulls, this seems pretty consistent with limitations that monohulls find themselves in. Simply go to any monohull blog of cruisers and read how they got from point A to point B and ultimately you will read how they motored at various times due to the needs of the conditions or limitations of the boats ability to sail. To say you would not have a boat you needed to motorsail on at anytime would mean you wanted a powerboat, at least to me, unless you were willing to wait for the conditions needed to sail, which for one reason or another people seem to just as soon motorsail to get going to their destination.
Cal28 I think you would find that if you moved to a Gemini, most any model, you would increase your living area and comfort but I think if you tried to move more gear (weight of payload) onboard, from what you are carrying now on you boat you would hamper the Gemini's sea-keeping abilities. So in a nutshell you can go larger in a multihull but you cannot go heavier in payload without careful planning. This is the whole principal as to why monohulls were used early on to carry cargo, they have a higher payload for the waterline length.
A multihull I like as much as some early Gemini's is the Catalac 9M. With modification, removal, of the non structural port side forward partition, the forward stateroom rivals the Gemini. The boats have been all over the world and they have the option of twin diesels for those days you need to motorsail. You can compare the Catalac's and Gemini's here for free Multihull Dynamics, Inc. - Home
You'll find there is not a lot of difference between the 9M and the Gemini 3000.