Well, first I would advise against "powerlifting only". Make it your focus, but keep other stuff going on.
Second, what are your three lifts? The box is a great tool for squatting. I have started to use it more and more in both DE and ME days. I have also forced my legs out much wider than I had previously squatted. We actually had a killer ME day last Sat, I hit a 600 belt only reverse band off the 18" box, lots of fun.
Personally, I have really enjoyed used the bands, chains, boxes, boards, and wraps. I look forward to trying out some suits and shirts, just because it's fun.