In December I finally stepped up to a carbon fiber tripod. I did not have the $500 budget and found the following article about Adorama's latest offering: http://www.shutterbug.com/news/122007adorama/
. I asked the forum, but no one had used one at that time. I decided to take the risk and purchased the $180 tripod and the $70 ballhead. This combination is rated to hold almost 18 pounds.
Since my last posting I have had the opportunity to use this combo in the field and found the quality to be good and the tripod is very solid. I shoot with a canon xsi and mate it up with a canon 100 - 400L IS lens and a 2x teleconverter.
Please bear in mind that I have not used the more expensive tripods. My comparison is limited to my old aluminum tripod from Ritz. Also, while I have found nothing to complain about, I have not had it for very long. It comes with a case that will allow you to pack it with the ballhead on. Its a tight fit, but it works.
Just food for thought. I know if I had a larger budget, I would have purchased a well known name brand. On the other hand, I am now that much closer to purchasing my next lens with the savings.