But JL prestige does offer a far more refined range of lasts. The SC does look a bit more eastern european with higher walls and toe boxes. The best looking SC last is the classic, but still compared to JL 7000 it is a bit rough IMO.
What is most important? Hand-welted is nice but really have no function in reality. A recraft of JL replaces eveything incl inner sole and welt etc.
As far as I know John Lobb prestige are only available on the 7000 and 8000 last. I have to agreed the SC classic last is more elegant last than others they offer imo. SC do have a few quirky style but if you choose the right style they always look very elegant. Just take a look at medtech_expat's collection.
I am not a expert on shoes but I have own the JLP 7000 and 8000 last, the 7000 last just look bulbous compare to the SC classic last. The finish and construction on the SC is on another league. As for hand welting here what our resident shoe expert DWFII have to say.
I don't think SC shoes have a built in arch supports as such. It's just how they shaped the waist it hugs your arch giving you support. It took a few wears to get use to it but now they are the most comfortable shoes that I have.