I don't have the Big Country series, but I do have a few Blackjacks, old and new, and they are fine cutters. If you're planning to use them in an at all hard way--and I'm not talking busting into tanks, but just light chopping/limbing and breaking the occasional joint apart--Swamp Rats are superior knives.
Do you have a source other than the Knifeware.com site for these? If not, it seems to be splitting hairs price-wise. $105.00 vs. $128.00 for a Camp Tramp, or even (if you want a smaller knife) $88.00 for a Howling Rat. You will have a couple/three weeks to wait for a Rat, but you have superior steel (for absolutely everything but corrosion resistance) and an unconditional lifetime warranty.
Like I said, I like Blackjack (though I like the ones made out of 52100 and A2 more) and they make good knives, but if you like the look of the Rats, I think the not-so-big price difference is worth it.