Typically underperform? I suppose that might depend upon one's definition of "perform"?
I regularly catch HBG that weigh between 1.25 and 1.5 lbs, I never have to worry about them overpopulating the pond and stunting, (matter of fact, they help control my LMB yoy), and a HBG will hands down outfight a comparably sized BG (and I suspect a CNBG as well) anytime.
That's my kind of underperformance! 
Tony, I love your kind of "underperformance"!
I believe it's a big mistake to compare northern ponds with southern ponds and why I don't ever give advise about ice fishing...
I recall Ewest posting about growing some of Todd�s CNBG to 1 lb in 12 months and this is our growth rate as well.
I have hit near 1.5 lbs in 18 months a couple of times.
I was shooting for 2 lb CNBG but fish kill of 2011 set me back but maybe some day��
There is absolutely no concern about CNBG over population if proper management techniques are applied.
