H Dr. Blue Dun,
A very good question. I think that most of us are not very knowledgeable about Spey Rods. We have a good number of Spey casters in the North West that fish for Steelhead and Salmon. Although there is not a lot of Salmon fishing due to restrictions.
A Switch Rod has a double grip like a normal Spey rod. They are not as long as a Spey Rod and can be casted with one hand, or used with a Spey cast, or with a double handed over head cast. They are great to make a long roll cast. They start at about 10'6" and maybe a little longer but not much.
I had a double grip rod made in Alaska thinking it would be great for Salmon and I could cast with one hand. I found that with a one hand cast the bottom grip got in the way or was awkward. I had the rear grip cut back into a fighting butt. My rod was 9'6". This was back in the late seventies and I didn't know I had a Switch rod made.
If I had known about two handed cast I may have liked it.
Beulah Switch Rod