After having used various versions of Comodo Firewall for several years I had to bid it goodbye today. Perhaps not as much Comodos fault as Firefox's, but after the update to Firefox/2.0.0.13 the Ff session load times with Sandboxie were over 20 seconds. I also could never get my new Vista notebook to find my printer. So today I switched to Online Armor Free and now sandboxed sessions start in about 10 seconds and I was able to configure printer sharing. For 60 I'm somewhat pc literate, however, Comodo and all of its great versatility are beyond my reach.
IMO comparing CFP v3 to OA Free is like comparing apples to oranges.
OA Free is a firewall with some HIPS capability.
CFP v3 is essentially a HIPS with firewall capability.
Power has its price, and a leaktest result is just a small part of the big picture.
OA Free maybe easier for you to configure, but only you can determine how much you can risk with less security and control.
I have been using Firefox for everything except financial transactions for several years now, but I would probably ditch it and switch to Opera before I changed security software, since I do a lot more with my PC than surf.
IAC, Firefox releases new versions quite frequently; why not wait a week or so and see if they fix the problem in 2.0.0.14?
Also, was there anything new in 2.0.0.13 that you found essential that wasn't present in 2.0.0.12?