Ollie

Slightly contrary view — 70% merino means 30% something else, and if that's nylon it should be more pill resistant, but if it's viscose or acrylic it'll be worse. Check the label. Acrylic pills form hard little beads that don't shed, which is why they look so bad so fast.

Shoulders fit is the whole ballgame, everything else is negotiable, so buy it. Sleeves shorten from the top (at the shoulder seam) when there are functional buttonholes, because cutting from the cuff would destroy them. That's a harder job than a cuff shortening and you're looking at maybe $60-90 rather than $25. Ask specifically whether they can shorten from the sleevehead — a lot of dry-cleaner tailors will say no.

Right — they open the armhole, pull the sleeve up, re-set it and re-do the lining. Two inches is on the edge of what's safe because the sleeve tapers, so the cuff opening ends up slightly wider than intended. On most blazers you'd never notice.

Secondhand changes this maths completely. Wool coats are one of the few garments where the used market is genuinely good, because people buy them, wear them six times and give up. £400 buys one excellent used coat and one decent used coat with money left for a tailor.