MBB on a diet (9 kilograms)

[Karl42]

I much prefer the British guy's seat angle adjustment mechanism. Simpler, faster and doesn't alter BB height. Less moving parts to possibly malfunction down the line.

Lowering the BB height is necessary for optimal power output while climbing:

One last thing. Trust me: low bottom bracket is very, very, very important for overall performance.

So for optimal power output in the hills and lowest drag in the flats, you really want to alter both seat angle and BB height, unless you settle for a compromise between the two that meets your style of riding.