It drives me mad when people lazily refer to "knee-high rough" at Muirfield. HCEG is a club with a relatively elderly membership, many of whom are far from expert golfers. They also like to play quickly. If the course really had fairways as narrow as is frequently suggested here, with ball-eating rough as close to those fairways if you believed the reporting on GCA, then no-one would ever play the place and the members would hate it. I am very fortunate to play Muirfield a few times a year. I reckon I lose on average one ball every other round and I am far from an elite golfer. The narrow fairway/deep rough schtick is so exaggerated it's boring.
Yes, in wet, warm summers the rough can get deep. For those unfamiliar with links golf, that's true on every links. Yes, before an Open the playing corridors get a bit narrower (not that much, though). No, it's not some Mackenzian wide fairwayed Nirvana, but then nor is TOC (or ANGC, come to that) any longer.
Where Muirfield beats Gullane 1 hands down is in strategic choice. Gullane asks one question on most shots. Muirfield offers so much more in the way of decision making and real, strategic choices. Gullane is a more aesthetic site and no doubt has better views. Muirfield is far and away the better golf course. There are real benefits to be had from being on the right side of the fairway on almost every par 4 or 5. The par 5s are as good a set as any in the world each managing to require thought and offer choices on each shot.
Frankly, I'm not convinced there's a single hole on Gullane 1 which, if transplanted to Muirfield, would improve Muirfield as a course.