It can work. ...But.
While building my own -6a I was in a partnership that worked really well 98% of the time. We scheduled on our own Yahoo "Group", and rarely had any conflict, sharing maintenance chores, etc. After mine was built I wanted to sell my 50% interest, and this presented a difficult problem.
First, I was limited to the local market, so instead of a few thousand potential buyers I was limited to the PDX area. Finally, partner and I decided to sell nationally. In short order it was sold to a nice guy from Memphis, TN, with much other interest, and sold for just a tad under what others were going for, so we were happy.
We had no formal agreement, just shared everything 50/50, filling tanks after each flight ourselves. If I do it again however, I would have a written agreement, just good business.
I am pretty sure that no matter who we partner with, no matter how compatible, there will be inevitable conflicts. In our case, equipment upgrades, VFR vs. IFR. Kinda like a marriage...
HTH,
Jerry