Without a shadow of a doubt the F9 is far easier than the B9; if you're not better than -6 at worst after 9, you'll be fighting a very tough battle to break the magic 60 mark for guaranteed qualification.
Simple fact is that on the B9, you've got to hit six approaches of around 170yrds+. Slightly off-ding and you're putting from outside of 15ft the majority of the time. Add in the fact of the greater variance in up and downslopes and three holes with significant amounts of water by the greens and you've got a much tougher 9.
Just wait until you've got champ greens on the actual main event; anything slightly off-ding and you'll be putting from the front of the greens. Anything overclubbed on some holes (11 and 14 being prime examples), and you'll be faced with a short chip down a sheet of ice which'll be near impossible to stop. Definitely thinking of practicing with the Cally Spin balls once we're faced with that challenge.