In reply to wannabeagoat:
I'd say all the boots mentioned are good at the same thing i.e. Autumn and Winter walking, scrambling, crampon walking, steep crampon walking, short bits of ice climbing (single pitch, low grade). Some are better at one bit or another. My thoughts:
> Scarpa Manta Pro - Is this more a winter walking boot or is it a serious winter climbing boot?
It's probably the most solid of the 4 you've suggested i.e. best for extended crampon use. It is however the heaviest and clumpiest so the least dextrous. Less suitable outside of Winter. By far any away the most weather proof and durable of the 4.
> Mammut Monlith - Is this boot weatherproof enough for UK (Wales, Lakes and Scottish) Winter conditions or is it too lighweight and "leaky"?
The lighter weight boots rely more heavily on the Gore lining. Once it's gone, that's it. Ok in Summer and Spring walking too, but a bit stiff for me.
> North Face SK4 - As this doesnt have a full rigid sole is this sufficient for climbing or is it just a poor cousin of the SK6 which will be soon found out as I try to progress through the Winter climbing grades?
None of them have fully rigid soles...? The S4K is a great boot for bits of everything. I've used them as a Summer walking boot in the highlands, on the Mer de Glace, a small amount of ice climbing, and for long technical scrambles. Not a poor cousin of the S6K. A completely different boot for a completely different job.
> Trango Cube - Will this boot also be found out in UK winter conditions given the sodden wet and cold conditions we get
Very lightweight. Less supportive than others, I'd suggest more of a scrambling boot which you can occasionally attach a crampon to. Great in Summer and Spring, but not for Winter Climbing by any stretch.
> I really like the Scarpa Manta but I dont want to get a boot that is great for cold wet walking and winter scrambling but gets found out once you start to try to climb?
Sounds like it's the most suitable at the moment. However in 2 years time will it be right? If you get more heavily into the climbing side of Scotland in Winter would you have been better off biting the bullet and getting a B3 in the first place? Some of them are as comfy to walk in as a B2. Salewa do some which soften for walking and stiffen up for climbing (use and allen key in the sole). Scarpa Rebel Ultra has a very soft upper for comfort and dexterity, but are insulated, and B3? La Sportiva's Trango Ice Cube looks to be the same sort of thing.