Belts are a good question and I always wear one, due to carrying my mobile phone on a belt pouch. The removal is, I think, to help reveal anything sewn into the belt that might not be read by the arch.
I have used cargo pants in the past and found them very useful but that was before the current times and I do not know if they are viewed differently. I have worn braces on a suit once when travelling (through MAN
to IOM as it was a journey I particularly recall, just over two years ago) and there was no concern from anyone.
I support the
gilet idea as being very useful as it takes weight out of your hand case (phone, MP3 player, eBook reader and digi camera add up) and allows you to get more into the hand case. (or to enable your female travelling companion to get more things into YOUR hand case.
Ouch, that hurt)
Of course, any airport that has the new millimetre wave scanners will undress you - without you having to do a thing!