Hi Eric and welcome,
I agree with Bob, go for the bigger/heavier weight bearing capacity as it could pay off in the future.
I have a cheaper tripod that a bought my wife years ago and just this weekend tried it out with my 100 - 400mm f4-5.6 L. When the lens is level its okay but once the lens is elevated or depressed beyond about 45 degrees it won't lock and quite easily creeps up/down.
If you want to edit any of my images to demonstrate points/techniques to either myself or others please feel free to do so.
Still learning with Canon 40D, 28-135mm, 100-400mm L and Elements 6.
Any Advice greatfully received.