The way I understand it is that if you hold a current comp check you dont need a BFR but as soon as the comp check expires you are limited by when ever you completed your last BFR or initial issue
E.g. If you sat ur cpl in march 09 from then you have been comp checked on 135 ops. Then your comp check expires in aug 11 and you dont renew it you would need to complete a BFR to carry passangers even privately. Obviously if you wanted to do hire or reward you would need a comp check anyway which would count as a BFR for the 6 months that it is valid.
I could be wrong but this is what I explained to my testing officer when I did my C Cat and he agreed.
Dont know about the ifr renewal though.