Thanks for the post, valid points indeed.
I took your advice read a few of the guides, and my list of questions to him is getting longer, I've also added yours.
As far as I know - the plane is due to cylinder replacement in about 300-400 hours, and the estimate is $6700.
I don't think he has a "saving for unprecedented maintenance" fund, nor an engine fund.
My main concern is breaking the co-ownership - since by the time I get all my ratings and hopefully start instructing - I might have to move.
We'll have to figure that too.
I will meet with him tomorrow and mention these topics, see where it gets us.
Thanks again.