In reply to Jamesrlee:
> ... it may be the case that the sportiva Gm and the scarpa 6000m may be overkill for the alps and Scotland but the Nepal's may not be good enough for my planned trip.
I would say that is exactly the case.
It really depends on you, your feet and a few other variables, like the weather at the time etc, but you can get away with Nepal Extremes at those kinds of heights, as you don't have very snowy high camps, but the early frozen start is still an issue.
People get away with all sorts of things up to 7000m (I got overtaken on Aconcagua at 6600m by a young guy wearing Sportiva Trango S boots) but it's always a risk and again, depends on the individual - and accepting the risk that you might wreck your trip with insufficient boots. Personally I wouldn't risk it and if you think you'll never climb high again, hire or borrow or get 2nd hand double boots for the three days of high climbing in the Khumbu and buy Nepal Cubes for your alpine and Scottish climbing.