It has held up well for me. In fact, for a while, I was only using SBP and Acrylic Glanz to touch up and it worked very well on my garage queens. I just ordered a second SB Pad and another SBP because I've almost used mine all up... I find myself wanting to polish (or fill) all the swirls on my car, whereas before, I lived with them because I dreaded polishing.
I could see getting away with using Acrylic Glanz over SB for quite a while, as it holds up well even in the rain. I personally prefer to use a durable carnauba over it though to preserve the fillers as much as long as possible.