The Wulff Ambush line is my go to line for Switch rod for good reason. It is ridiculously easy to roll cast and make Spey casting a lot easier to learn. It has a 20ft tapered head joined to an integrated running line. The key to this line success is its concentration of mass near the butt end (the part joining the running line). When the head just overhangs the rod tip, most of the mass is right at rod tip making it very easy to load with a D-loop.
This line was not specifically design for double-hander. It was meant as a line for tight quarter roll casting and single hand spey casting. However, with the rise in popularity of shorter Spey rods and Switch rods, this line found its niche. Gary Sandstrom designed the line for Royal Wulff. You can read more about his design philosophy and inspiration here in this newsletter:
For Spey casting with Switch and shorter Spey rods, this line match well with RIO versi-leader from 10ft - 15ft. For floating and intermediate tips, I typically use 15ft versi-leaders. For faster sinking tips, I stick to 10ft versi-leaders. The Ambush line is now available from 195 grains all the way up to 550 grains.
Here is a chart I created to reference Wulff Ambush line grain weight: