Note: The Gitzo GT5540LS 6x Carbon Fiber Tripod has been replaced by the very-similar Gitzo GT5541LS.
The Gitzo GT5540LS 6x Carbon Fiber Tripod review has a prerequisite - read the Gitzo GT3530LSV Tripod Review first. This will familiarize you with the typical Gitzo features. Then, if you need a really solid, vibration free platform for your camera and large lens, come back to this review.
The biggest functional difference between the GT3530LSV and the GT5540LS for most photographers is the reduced vibration. The GT3530LSV will handle the biggest lens Canon makes, but the GT5540LS will hold the same gear even more vibration-free. I most often use this tripod for the Canon EF 600mm f/4 L IS USM Lens and Canon EF 800mm f/5.6 L IS USM Lens - when I do not have a great amount of hiking to do. I have used lenses as large as the Canon EF 1200mm f/5.6 L USM Lens on the GT5540LS (shown below).
Yes, there are some penalties to pay for getting the ultimate tripod base for your big gear. The first penalty you will encounter is the price - This is not a cheap tripod. The next penalty you will suffer is in regard to the GT5540LS's size and weight. Even though it is made of Gitzo's 6x carbon fiber, it still weighs 6.5 lb (2.96 kg). A reasonably small folded length of 23.6" (60 cm) does not tell the entire story - it is much larger in diameter than the GT3530LSV.
The Gitzo GT5540LS 6x Carbon Fiber Tripod reaches a maximum height of 59.4" (151 cm) when extended. With legs opened wide, a minimum height 5.5" (14 cm) can be achieved. A load capacity 55 lbs (25 kg) should handle anything a photographer is interested in shooting with.
Prior to getting the GT5540LS, the Gitzo G1548 Carbon Fiber Tripod (above right) was my large lens tripod of choice. The GT5540LS's G-Locks are the biggest improvement over this tripod. They are much nicer to use. The GM5540LS weighs 6 lb 4.8 oz (2.85 kg) - 5.2 oz (.14 kg) less than the GT1548. This difference is not huge, but nice.
Had the Gitzo GT5540LS 6x Carbon Fiber Tripod not come along, I would have been perfectly content to continue using the GT1548. But now, having used the GM5540LS, I would have a harder time being content with the old pod.