Which Gitzo Monopod 5541 or 5561T ????

Within the next year I will be buying a Nikon 400 f/2.8 G lens. Trying to work out which tripod to get. I know each one has gone their pros and cons like the 5541 is 2" taller but the 5561T will fold up shorter.

I am starting to lean towards the 5561T but my main concern having 6 legs the last leg is very narrow, I think from memory less than 1" in diameter. Maybe not as steady as the last leg on the 5541? The 5541 having 4 legs the last one is a lot thicker. I do a lot of Landscape photography.

Which one would you get

One last thing the grip on the 5541 is it the same in diameter as on the 5561T?