You're always going to get this perception home advantage whether you stage it at Belle Vue, Ipswich or Scunthorpe. Andy Smith won three British Finals in a row in the 90s at Coventry when there was a far stronger pool of riders than there is today, and guess what - he was a Bees rider at the time!
I think there is mileage in moving it from track to track - its a shared event after all - but if one of the riders races at that venue every week, immediately everyone will say he has an advantage. It's more pronounced at Belle Vue because one of our two GP regulars (at least the one who bothers to ride over here) is a Belle Vue rider.