I just recently bought a switchback xt. any thoughts on a sts for this bow
(single or double)

We have a lot of shooters put them on switchbacks and xt's. It's not that they need it but it takes that last little bit of vibration out of the bow.

The STS is great and I have them on all my bows.

What Is Sts?

Here's some more information on the STS
http://www.stsarchery.com/

online store to purchase sts (http://shop.3dshoots.com/product_info.php?products_id=766)