So far I like the results and I am even thinking of getting rid of the second Vyper group in my army and pick up a Wave Serpent with something inside - probably Fire Dragons. The thing about it though is Vypers have a lot of hidden abilities, and I'm worried that changing up just these two units will alter the way the army plays drastically. Namely, it would become slightly more direct, and I would lose some of my ability to throw down speed bumps and give out quick cover saves when I need it.
It's not the loss of firepower, it's the application of that firepower that changes, and my ability to support the rest of the army. I'll play around with the idea for now, but I wanted to throw my thoughts down.