I do use a clear line, and no loops based on past experiences. There are spots I like to fish on the east side of Monomoy (no one else bothering, lots of fish) that will require the 325 grain QD, so bring it. If you don't have the clear line yet, I would recommend the 444 clear intermediate because it casts well and takes a nail knot. Many other brands do not take a nail knot (imagine that?
In the spring rush, when the fish are coming around the bend in waves it doesn't really matter if you ask me. You could catch fish with anything that puts the fly in their face.
In July and August, totally different story - I'd even dress to blend into the ambient colors then.
I really hope Ron comes, he fishes it more than I do and has some interesting perspective on what works and what doesn't, where to fish and where not to, etc.
I ended up on Rip Ryder with one of the Monomoy regulars one day. We were walking back together on the east shore toward the "tree" and I saw some shifty shadows. I stopped to cast, he said "don't bother, nothing there". I tied on a crab, second cast >THUNK< the shadows were all keeper sized bass.
Another day, the shuttle was making me wait (and wait and wait) so I started to fish the drop off as the tide swept over it. A clam digger worked the sand as I cast. The hole was loaded with stripers, nice size (but not K's). Keith started to head over so I reeled up, the clam dude said "never see anyone fishing there".
Moral I learned from it all: although the quintessential fishery on Monomoy is the skinny current sweeping over the common flats or (or guzzle or crib) there are plenty of fish in any logical station at any given time.
Oh yeah, answer: if you got the green, go for the clear 444. It's a great flats line.