As a recent purchaser, I went through the same debate. Partnership? Own? Keep renting the M20J? At the end of the day, it probably makes sense to go with a partnership to reduce costs, but at the same time now you have to worry about personalities, what happens if they want to leave, politics, etc., and needless to say: every decision has to be vetted with the group. You can't for example, decide to go with GI 275 b/c maybe the other partners want Garmin G5 instead.
With your own plane, yes the financial risks if something goes terribly wrong certainly exists. But, you can mitigate it by careful planning and saving up. You can take your family for a vacation and choose to extend by a week if you want to - without paying minimum charges per day nor having to coordinate. You want to upgrade to a longer body Mooney- completely your call. You know what the state of the aircraft is every time you get in it. Things stay the way you left it. You can plan ahead for fuel if you expect gross weight t/o the next day. And finally. it's YOUR OWN PLANE!