Besides the plane, check on the groups financial position. If a group has a sensible engine fund, then engine hours don't matter. If it does not, then the share devalues with every hour flown. Check on the age of the instruments and avionics, as well as the airframe.
Shares are not easy to sell. However I calculated that less than 70 hours would give me a profit over renting when I bought a group share in January 1990. I flew that within a year. I'm still in the group.