I am extremely familiar with the Jefferson 52 Monticello. In fact, I have one listed for sale right now in Tennessee.
I have been on a lot of Jeffersons and especially the 52, both marquessa and monticello. IMO, the monticello is more boat in the 52' range just about ever made. I simply LOVE the layout of the vessel with it's 2 salon set up. Way more space than something like the 53 hatteras. Interior woodwork is top notch. Engine room access is going to be a little tighter than some other vessels in this size range but again, the flip side of that is having 2 large salons and great living space. On sea trials I have found the monticello to be very responsive and handles well. *Only other item for longer coastal cruising will be getting a good set up for a dinghy. *You can use weaver snap davits or sea wise system or even better- a full crane davit on the foredeck with a small 11' boston whaler set forward of the foredeck bench seats and just aft of the pulpit so as to not block the view at the lower helm. *Personally, I really, really like the 52 monticello for a coastal cruising motoryacht. *
Not sure you will get too much better fuel economy running on one engine at a time but that is a topic that has been debated here if you do a search.
Let me know if you have any other monticello specific questions.