I am not familiar with Scandi head at all... I just read some information from the internet. They said the Scandi heads are comparable to the skagit head, but designed for stiffer rod / longer leader / touch and go cast for lighter flies. This remind me some underhand style cast. I was wondering the reason for 100/2oo grains lighter Scandi head... thanks
Skagit heads typically have a shorter front taper, which puts a greater amount of mass forward to enable turnover of larger flies.
The reason the Scandi head is much lighter (for the same rod) than the Skagit head is it is used with a kiss & go, air born anchor. Single spey & snake roll casts. As such, it only needs to cast a long leader and the fly.
A Skagit head, on the other hand, is casting a 100+ grain sink tip as well as the fly. To do this on my Echo 1307, for example, I use a 27 ft 500 grain head, 13ft of T-10 (130gr) and medium to large cone head/dumbell eye flies. Water born anchors, Skagit style casts.
Dry flies, same rod, 40 ft 400 grain head, with a long front taper, 13 ft mono or floating poly leader. Kiss & go scandi style casts. The flies may, at times, be bulky and a bit wind resistant. But nothing like what a Skagit head can cast.
Now I can stretch the limits of that Scandi head by substituting a lightwieght sinking poly leader. But what am I accomplishing? The head just got longer. Meaning I need more room behind me for the D-loop. And, because of the long front taper and the lighter tip, I can't turn over anything more than lightly weighted flies. So I cannot get down like I could with the Skagit head and a heavier sink tip.
Let me clarify what I mean when I talk about turn over. I am not interested in upstream casts, dead drifting, stack mends, or any of that. As such, I want complete control of the fly from the time it hits the water. To do that requires a clean turn over.