IMHO it's the lack of regulation that SRG has over FISOs can make them a liability. I know nothing of Barton, but can give examples of South East Aerodromes where FISOs give ATC clearances and are generally a liability. SRG want stronger controls over them and over A/G stations (which they have no regulation over). AFIS is a good system I think, but pilots have absolute responsibility for their actions and what they do. In the air a FISO can give a FIS and ask for a pilot's intentions. They can't ask you to join in a particular way, they can't give you any clearance at all. It's all down to the PIC.
However, a good FISO ie Fairoaks will give you all the information you need to make a good decision. This info only backs up what you see and assess with your own eyes.