Good Point Smalma, it does make you think:

336 fish over two years for two guys--thats 84 fish per guy per season. Multiply by 30 fishermen total for 2,520 C&Red fish (30 damn fine fishermen!) Given 5.1% lost to hooking mortality, you end up with a loss of about 130 fish. This makes it clear that C&R is not a no impact use of the resource. But it's not likely that C&R fishing effort would get this high because as you said, the total escapement for the river is around 1,100; every fish would not only have to be landed but would have to be C&Red more than twice, which is not very likely (unless those were some real aggressive fish). Come to think of it, wouldn't this likely provide a reasonable buffer against overfishing in any C&R situation?

In a C&K scenario, if each of the 30 guys could keep 5 wild fish per season, that would be a loss of an additional 150 fish (or 900 fish with a 30 fish limit). Even if regs stated you had to stop fishing after you bonked your limit, there would still be a larger loss, compared to C&R, only now with substantially less fishing opportunity.