If you are in an area with poor reception, it might be a bad idea. Though I see you are in Manchester, so you should have no problem. If I bridge the antennas in certain parts of my house I can make it lose signal, but it was not often I would do that accidentally.
I have the free bumper which does seem to help some people. Personally I see no real difference. In Manchester proper I never have a problem, as the signal strength is very high.