I think it seems more important to maximise your chances of winning money than it is to maximise the amount of money you might win. The higher offer comes with a lower margin for error -- two sucker questions on, say, for me, soap operas and I'm done and bye-bye that £50k or whatever the higher offer is. Assuming I'd had a reasonable cash-builder round then there should be something north of £7k in the pot anyway -- I'd be happy with that, and the extra margin of safety that one more "allowed" wrong question seems worth looking a bit timid. And in the final chase it seems important to have as many people as possible as well, an extra few steps to start and potentially fewer overall gaps in the teams' knowledge.
If I'm ever on the show, Sqad, you'll probably find me the boring one... but then, perhaps this also explains why my application for the show a couple of years back was rejected!