As regards hour builders in a syndicate, I've seen on both sides of this. But having been in your position many years ago I decided to buy the aircraft outright rather than buy a share.
The reason for this was that because I wanted to get as many hours as possible in as short a time as possible, I didn't want another syndicate member getting in the way and flying it when I wanted to. Also I didn't want another syndicate member damaging it which would preclude my using it. If it got damaged then it would only be myself to blame. Plus I figured that after flying my required numbered of hours it would be easier to sell the whole aircraft rather than a share. As it turned out the aircraft was very reliable and I was able to do around 170 hours in four and a half months. I even sold it for a small profit
Fast forward quite a few years and now being a syndicate member, I wouldn't have wanted my younger self in my syndicate because of the reverse of some of the points in the previous paragraph. In essence I would not want a syndicate partner whose only aim was to get as many hours as quickly and cheaply as possible and then move on as quickly as possible.
As a general comment I suspect the average syndicate member probably does around 10-20 hours a year. Obviously some more some less. Get someone in who is now doing 100 or more hours a year and that is bound to lead to friction.