Genghis - a 'perceived' availability problem was one of the reasons several people decided the leave the group, just as we discovered the state of the finances.
The group had (understandably) restrictive rules around weekend flying. But of course the aircraft was still under-utilised on weekdays, whilst some weekends you couldn't get a look in. Other weekends the 'plane sat in the hangar, and not always due to bad weather....
So a perception of lack of availability at weekends proved to be a wedge which led to the final straw and the proverbial camel.... Although I agreed that weekend rules were necessary to avoid monopolisation of the aircraft, a more pragmatic view on what should be allowed would have made life easier.
I for one flew almost exclusively at weekends, and wouldn't have appreciated it if the 'plane had never been available, but at the same time I had hoped the occasional (1 or 2 per year) weekend trip would be possible, rather than bumbling around locally with a 4 hour max. booking limit (2 hrs in winter).
I think the decision on whether to join a group is often made upon the basis of hourly cost, but I would advise tempering this with considering what you want to DO with the aeroplane. If you want to join a group because you want to do some touring and can't afford the four-hour daily minimum charge applied by many clubs/schools, you need to find a group that not only has a suitable touring aircraft but that actually encourages touring by its members. Differing aims and aspirations amongst group members is likely to lead to disharmony, which defeats the object (for many) of joining in the first place...