I noticed the Compete Blog post about XM vs. Sirius about two weeks ago but did not comment on it then; however, someone at Compete noted my post on Akamai Measures Digital Music on December 11th.   If people want to contact me directly - it's best to send me mail [now.seo  at .... gmail.com] (let's give the email extraction scripts a headache!)

My original post was about metrics of music downloads being tracked via Akamai - nothing specific about XM or Sirius (except music downloads were being tracked on both satilight radio stations):

However, I did SEO work on Sirius radio about 3 years ago (when XM was much bigger than Sirius); including comparing all the common and unique backlinks links between XM and Sirius for Acronym Media (I did some freelance work for them back then, and for Conversion also - I don't have any direct relationship with either firm today).

Getting back to Compete's blog post comparing XM and Sirius - they kinda look like equals based on Compete's chart - but I doubt that's true, even now.

The time period covered by this chart (which is different than the one year of data you can pull out of Compete today) overlaps the period of time I worked on the Sirius account.  At the time, XM had 3 times the number of subscribers that Sirius had - don't know if that's still true - but based on that fact alone - I'd say the traffic charts produced by Compete, or HitWise - are not telling enough of the story to be that useful yet.

I pulled this chart (above) from Google Finance - it compares the stock price of XMSR and SIRI during the same time frame that Compete produced it's traffic chart of unique visitors.

Here's what I would say.   I wish the charts I saw were more than web traffic and also included a way to tie in financials (when it involves financials of companies) equating the value of a unique visitor in dollars.  The data is there - in the chart above.   Compete has an estimation of Unique Visitors.

Two things -

1. Compete is measuring web traffic (uniques) to xm.com and sirius.com but the real activity is subscribers who are listening to satellite radio using a receiver.   There's no real reflection of what Uniques mean here.  But if we're talking about traffic (and not subscribers) an Alexa chart is about as useful as the one Compete provides.  Neither service really tells an accurate story.
2. Without merging financial with the web data (and that data is available now) it's hard to decide if the traffic, accurate or not, means anything.  I don't think it does at this point.

The Alexaholic traffic chart  is not accurate.    BTW, Motley Fool wrote an article that called both companies lousy investments and suggested they should merge.