In reply to libertine:
For most Alpine summer stuff B2s will be fine and preferable. B2s will also be fine on easy Scottish winter stuff, i.e. up to grade 2 neve slopes and ridges.
However, you mention Scottish mixed climbing which sounds like a more serious ambition to me. If this is much more than mixed ridges then I think you need B3s. The last thing you want is crampons popping off or more likely, your boots are not rigid enough to get good feet placements.
You also need to bear in mind that there are B2s there are pretty flexible so closer to B1s. The B2 classification is therefore not all it may seem so you need to look at each boot carefully.
Re the walking in, modern B3s in my view are perfectly fine for the walk in. I use Scarpa Phantom 6000s which are a pretty full on B3 boot and find them perfectly fine for walk ins (including using them on Ben Nevis so the full walk in to the north face). The bigger issue is they wear more quickly as the sole is not designed for long walk ins unless on snow.
Finally, your ambition now might not be to get into too serious ground but the bug will grab you (guaranteed) and you might quickly regret not getting a B3 or B2/B3.
As mentioned the Scarpa Mont Blanc Pro GTX are nearly half price now (I assume as a replacement will be coming out soon) and are a B2/3 so are excellent value and could well suit you ideally (if they fit well).