It is good to know that some people think you should pay for a PBX. There are clearly some good people in the world. However, you really don't need to spend all that time and effort choosing what PBX you want, finding somewhere to house it and paying someone to maintain it.
Once you have made the decision and purchased your PBX you will need to be very careful about changing your mind - any alterations will cost a fortune.And then there is the long term tie in - we have heard (and seen) contracts for 8 years. Birchills contract is simpy for 30 days you can change your mind at any time.
So why not check out the features that you get with a new system compared with the old systems. Maybe free is better after all!