I even want to buy now Tier 5, Tier 10 if available. You can track a lot of essential information like CTR, Estimated Traffic, Serp %, PPC Value and tons of other metrics. I was surprised with what Nozzle brought, actually I only bought Tier 1 to see how it was but switched to Tier 3 after testing it for 30 minutes.
As someone who has used a lot of keyword tracking tools in the past, I recommend you buy it now. It's definitely the best investment you'll ever make.