I think the biggest issue, which non-radio fans will be quick to point out, is that a FIS is generally of negligible use to the PILOT as far as traffic avoidance goes. Very few PPL instructors will tell you this, unfortunately.
So (save specific situations like flight plan flights abroad etc) almost the entire use of an FIS is to have someone around who you can be reasonably sure will hear a mayday call if you have to make one.
Whether actually talking to e.g. London Info is any better than just maintaining a listening watch, I doubt. Nowadays I rarely talk to them. I know of very experienced pilots who do the same.
But, non-radio I would not like very much. Try getting into Shoreham for example on anything resembling a busy day. Your flying options are severely limited.