I have been using Span nonstop from the moment I downloaded it. This plugin has taught me a lot about my mixing and highlighted problem areas that I couldnt hear before. The display is great. Big and Bold, (ideal for mastering) and very simple to understand. I use this plugin during tracking, mixing and mastering. I dont think I have another plugin that is used as much as span.
For a plugin that makes no noise whatsoever its helped me produce a better sounding mixes. I probably sound like an advert but no. The fact is I couldnt do without Span now.
Oh, and its completely free. What more could anyone want