In reply to rockwing:
As someone with wide (but not crazy wide) feet I've always struggled to fit boots, even winter boots that you might expect to have a bit more toe room. It's down to the shape of your feet as well as their width. I've found that a more asymmetric front end can feel tight irrespective of the overall width because the outer curve of the toe is just too slanted for me. We're all different and for every individual some lasts will work better than others, meaning that some models from a given brand could be better than others. So it's not just a case of one brand always being narrower and another wider, that's too general. Cue a lengthy bout of trying them all on in the shops.
That said, I have historically tended to find the more technical models from Scarpa and La Sportiva either a bit narrow or a bit curved at the front end for an ideal fit on me. I've also got a pair of the new Dolomite Miage Peak here on review, and I would call them narrow too - in fact, too tight for me, so Toby will be trying them (bad luck for me - they look fantastic). In recent years I've personally got on best with B3 boots from Salewa and Mammut. You could also look at Hanwag (though I've not always found them as wide as their Germanic origin might lead one to assume).
Where the boots are slightly less climb-oriented, at the B2 level, front end comfort can often be better in my experience, because the overall shape tends to be less curvy so you get a bit more leeway for the toes. A current example would be the new Scarpa Manta Tech, which I have on review now and am finding really comfy.
If your feet are a smaller size you may 'get away' with a B2 for all your climbing needs - depending on what you're doing in them of course, and where. For massive feet like mine the leverage on the sole makes B2s too bendy for sustained front pointing, so I generally seem to end up drawing a line at grade II.