The IT Crowd has 24 episodes, BBT has 134 and is still running. IMO that makes them kinda hard to compare.
And weren't the earlier episodes of BBT a bit different? I seem to remember they had more "hard" science/tech jokes that actually made sense (jokes that seemed like they would be quite obscure without an exact/tech background).
So, what if BBT had squeezed their ideas into a smaller amount of episodes?
Of course one could say that it was exactly that choice, that makes the one better than the other. And I'd have to give you a sort of kind of "yes, maybe". Because I don't know, sometimes the UK format series are a little bit too short (indeed, like The IT Crowd!!), but some US format series go on for way too long. I would hope there is some optimal middle road.
(but then maybe not, the first example that came to mind of mixing US/UK serial styles was Torchwood: Miracle Day, the worst of the series, IMHO. There may be better examples I'm not thinking of right now, though)
 How I Met Your Mother being a prime example. If only they would push it a little bit further, and then some more still, so it would turn back upon itself in a somewhat post-modern sense, by actually making the viewers just as bored as the "Kids, ..." at the beginning of each episode, their inner voices silently screaming at Ted to get to the bloody point and finish up the story already. This would of course kill the ratings, but they could sell the show to Belgium, the Netherlands and other countries where anti-humour is still appreciated :-P There is time ...