<<where the greenbar indicates (but doesn't tell decisively) how you will rank against competitors for keywords.>>
<The green bar does no such thing. The green bar is a measure of popularity, not precision or relevancy, and give very little insight into how a keyphrase will rank at all unless the phrases are in a non-competitive set.>
It does measure link popularity.. a higher link popularity equates to a higher probability of ranking higher. The green bar gives an indication of this link popularity. I am not implying that the greenbar is the cause of a particular ranking.
<<When I go to a site that has a TB PR which differs from what I would expect, I try and figure out what they are doing "right.">>
<That analysis takes a nanosecond. The site is acquiring inbound links.>
This analysis takes a nanosecond because of the greenbar's existance.
Without the toolbar installed, I would have to go to Google and search on any site I was interested in knowing about their backlinks, and I have no idea which sites I want to bother searching backlinks on. Having the greenbar available means that when I happen to land on a competitor's site and see that they have a high TB PR, I can do a backlink search on them, find who links to them, and see if those sites would be interested in a link trade (these is an easy way to find a large group of relevent sites).
It helps focus efforts.
<<Using the greenbar, I can focus my efforts on the sites that have a higher TB PR>>
<When you should be focusing on sites that will drive traffic to your site rather than believing that TB PR is an indication of the success of a site, a metric to determine traffic flow or an indication of how valuable a link is to the surfer.>
But it *is* a metric to determine traffic flow. Simply from my own experience, a PR6 page that links to be generates more click-throughs than a PR4 page that links to me. Aside from that that link does help me increase my PR which helps increase my position in the SERPs. If you don't believe this is true, then you may want to do a bit more research on the importance of PageRank.
<<or that a site's success is measured by sales>>
<I only deal with commercial sites, I haven't seen any folks that are willing to fork over any dough to see if their site about Muffy the Fantastic House Pet can achieve higher rankings.>
<There are plenty of sites that are willing to pay for promotion, such as sites for political campaigns.
I said- TB PR won't help get visitors to your site, position and a compelling description will.
You said- I didn't say that; you just took what I wrote out of context so it looks like I said that.
Your previous comment was- But when I have information, such as how PR works, I'm going to use it to help get those visitors to my site so they enjoy my content.
<I repeat- TB PR won't help get visitors to your site, position and a compelling description will. Further, checking position for a limited number of keyphrases in pointless. Check your logs, that is where the useful information is.>
In my comment of "But when I have information, such as how PR works, I'm going to use it to help get those visitors to my site so they enjoy my content." .. the word "it" refers to "information", not "PR." Knowing how PR works, and putting that knowledge to work to increase your PR, will increase visitors to a site. Adding more good content (which I spend a lot of time doing) will also increase visitors to a site and keep them coming back.