I fish for carp on the Potomac, which is a large, open river with frequent wind. The flies I use tend to be a size 6 and are weighted, somewhat "leechish" in appearance.
I can't imagine using a 6x leader and won't ever think about it further.
I tend to use a 8-12' leader of 30 > 20 > 10 pound monofilament and have hooked a couple of "hot" carp that ran quite a lot of backing out.
Frankly, I don't see the point in using light tippet for carp given the size of fish, conditions, and the quick-sinking flies I need to make a presentation to them. the heavier stuff just makes your life a lot easier and given the little room for error, why be a moron? (Read below -- I'm still a moron). With carp, it seems to me that stealth (or staying
completely out of the water, or on watercraft if at all possible) is about 95% of the game with sight casting. The rest is getting a good cast out in front of a feeding fish and hoping to get an approach.
If I choose to wade, I don't even expect to see carp since they skip town long before I can reach 'em.
In the interest of being honest, I did hook one last year (probably a 20-25 pound fish) usiing a TFO finesse 3-weight that I was *planning to use to catch the sunfish on a calm day out there. He ran me out, under a concrete bridge pylon and wore my leader through (4x leader).
I like to think I'm no longer dumb enough to not have my 8-weight in May, but we'll see this coming year
.
YMMV