Not sure why my work is getting pulled into this, but I can honestly say that I'd be surprised if he uses overlays and stickers on any of his work. Judging by the exceptional job he did with my Embryon, I can tell you that its definitely not an overlay. In fact, many parts were hand painted as oposed to airbrushed given the detail needed. I've seen quite a few jobs from him and all are at the same level.
Don't hesitate to use HSA for any restoration or clear coating. Your product is in safe hands from my experience. I would consider any comments about overlays or stickers with caution.