I haven't yet had the chance to sit down and listen to all the models side by side, but I've heard a few in isolation. It's sort of what you'd probably expect really - the .22 and .24 have better depth and headroom in comparison to their smaller brothers thanks to their larger drivers and cabinet volumes, and will be more effortless in larger rooms. The .22 and .24 also benefit from improved efficiency being an extra 3dB more sensitive.
The sound of the whole range I think will suit almsot any type of music - they're not boxy, they're not boomy, not laid back, but not too forward either, just wide open. When I say 'wide open', I really mean it! How they've managed it in comparison to the competition is beyond me. The only thing I would probably say is that for those into rock, you'd be looking at the .22 and .24 models, ideally.
The i-series was a mixed bunch for me. I was never overly keen on the DB1i and GB1i, which I assumed was down to their smaller drivers (although the GB1i could sound great with careful matching), but hearing the .23 makes mincemeat of that statement. It can't be to do with the size, as the GB1i's use the same size driver! Although, the .23's have a little more cabinet volume to play with. While I wasn't a 'great' PMC fan, this range is enough to change that view. I'm loving this range, and so far it's looking every bit as strong as KEF's R series.
In comparison to the TB2i, I think the strong points of even the .21 are enough to outperform them. The TB2i's will still be preferred by those who like their low end, and are used to the more laid back sound (in comparison to the Twenty), and those who like a bit of warmth. In my words, I would say the Twenty models make the i-series sound 'nice'.
TB2i compared to the .22? I would say there is no comparison...