Cap'n
I am of the species of rider known as "flat earth" and although I've done the Catford (once) and the Bec (twice) and after each one have vowed "never again"
They hurt like hell, you can't walk, talk or do anything coherent for 10 minutes afterwards, except question your sanity.
Having said that, the crowds and the atmosphere are great, and you get a wall of encouragement nearly all the way up, especially near the top......raise the skull and crossbones and give it a go - you might like it
Sorry I won't be out to watch - will be on the Isle of Wight.