I made the switch to a double handed rod 3-4 years ago now. Are they pricey? Yes. Are they worth it? Without a doubt. The reasons why have pretty much been covered by others posts but I will add one more.

Ease on your body. I do a lot of winter fishing with tips. A full day on the river with a single hand 10' 8 weight and a Type VI tip would send me running for the Ibuprofin for back and shoulder pain. With the spey, there is no false casting so fewer casts and using both hands greatly reduces the wear and tear on your body.

As for a spey not allowing you to "flyfish", that is bunk. You cna do anything with a spey that you can with a single hander. A single handed rod does excel in some areas, close in work chief among them.

If you decide to make the plunge, good luck! It can be addictive.