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 600 grains.
Here is a chart I created to reference Wulff Ambush line grain weight:
*Updated 12 Mar 2015:
Wulff Ambush line now also comes in clear intermediate sink (Ambush Clear Head) as well as neutral intermediate sink (Ambush Neutralizer).
The Ambush Clear Head is a great stealthy line for lake fishing as well as saltwater flats fishing. It has one the best intermediate running line I have come across so far. The running line has little memory, not overly stiff and neither too limber. It does not pile up on my stripping basket like most other intermediate running line. Instead, it will lay relatively flat on the basket and that helps tremendously in reducing tangle on the shoot. I also like the diameter of the running line, it is not too thin and gives positive comfortable grip during strip back.
For those who fish lakes and would like to have a slower sink line (1 ips), then the Neutralizer will fit their need. I typically use Ambush Clear Head for my saltwater flats fishing because of the faster sink rate (1.75 ips) and stealth (clear line).
It is also important to note that the Ambush Clear Head, being of faster sink rate is slight more challenging to Spey cast compared to floating head. It tends to stick to the water a lot more since it sinks faster. When using Ambush Clear Head, I typically make use of the Speed Poke to overcome this problem.
*Updated 29Jul 2016:
Royal Wulff recently added a 3wt (175gr @ 18') to their popular Ambush line. This is indeed good news for those into micro-spey. They also added half weight lines for better tuning. For example 8wt Ambush (290gr) now comes also in 8.5 wt (325 gr). For those into longer Spey rods, they now have 650 gr @ 30'. You can follow this link to the new Ambush Line Specs