farrow and ball exterior eggshell

i have a job to do where all the new windows are coming prefinished in farrow and ball exterior egggshell
the window company are giving a 8 year guarantee on the paint ,is farrow and ball really that good
i have all the old facias and pipes to do in the same colour but am a bit concerned about using f&b
surely tikkurila ultra ,would be a better option for me or any other paint for that matter ?