I used to be in a group like this. However rather than charging £190 per month (i.e. a fixed monthly fee independant on how much you fly), we used to buy 50 hours / 25 hours per year, then pay that rate per month by direct debit. If you flew less, you lost the hours. If you flew more, you paid for more hours. The more hours you bought up front, the cheaper they were per hour.
One advantage with the group I was in was that they had 3 aircraft. If one was down you could use the others. We used to pay about £70 per hour (eqv. x50 / 12 per month) dry and fill up when we returned the aeroplane to parking.
One trouble with renting an aeroplane dry is that some people will try and lean the bugger out of it to save a few pence here and there, and hence engine wear and tear could be higher.
It was quite a good idea though, I got to fly far better aeroplanes than the PA28-161's of the flying club for about the same price although the £30 per pop landing at the home airfield took a chunk out if you just wanted to go for a quick spin. In that case the clubs aeroplanes were better as they included landings.