Site traffic analysis sites, those that report your traffic to third parties, are commonly looked at to determine your site reach as well as for competitive intelligence. Most widely used are Comscore (paid only), Alexa (free), Quantcast (free), Compete (free and paid).
The question is why Compete Pro? What does it have to offer that Quantcast or Alexa do not provide? It appears that possibly their search analytics and referral analytics are the features not already provided for by Quantcast or Alexa.
It also appears that Compete Pro may be attempting to encroach on some of the products that Comscore provides for competitive intelligence.
Anyone have experience with Compete Pro (the paid version) and do you find it worth the subscription fees?