Years ago, I asked Ed about using a length of intermediate line behind T-14. He was against it because, not being able to mend the intermediate section, he would not have the control he wanted. You have to understand how Ed fishes a MOW tip/ weighted fly setup. Ed does not rely on the T material to gain depth. He uses it to maintain
depth. If he wants to make the fly rise up over some structure & then drop back down, he is able to do that by mending.
It took me a long time to figure out all this stuff regarding big heavy intruder flies. But the long & short of the [I]casting part is, the sink rate (T stuff) is less important than the core material
and the weight of the stuff. It takes mass (grains/foot) to turn over mass! T-14 is built on 35lb mono,
the lighter T stuff is built on lighter, more flexible stuff. A longer sink tip will take longer to get down, but it will stay down better under tension. Shxt flows down hill. T-14 weighs duh, 14 grains/foot. If the tip of your (Skagit) head weighs less than 14 grains/foot, it's gonna have trouble transferring the energy on down thru a length of T-14.
Anything less than T-14 lacks the mass required to kick over those big heavy flies. If it lands in a heap, you have no control over the fly until the current straightens everything out. A fish could suck it in & spit it out & you would never know it.
I operate on the K.I.S.S. method. Start off with either a 6ft or 9ft T-14 MOW tip, put the other one in my shirt pocket. Fish one rig long enough to get a feel for what it can & cannot do. Adjust as required.