I always wear wellies - and with shinpads. They fill them up quite tightly, and given I'm always getting into 'tight scrapes with loose deads', I'm way more concerned about getting my legs out unbroken than ultimate comfort! Everyone laughs at the shinpads, but I don't care. For digging they're a dream.
That said, I have been thinking about those posh Purofort wellies - the ones that look like Judge Dredd's boots. I'm just concerned they'll end up getting trashed like all the others do - wear off the rubber over the steel toecap, and get splits in the soles. £20 wellies I can stand that with, but £70. Unless, with the £70 ones that doesn't happen? Six years and like new sounds pretty damn good.