There is no difference in an analog's speed verses a digital's speed as long as they are rated the same... What weighs more a pound of lead or a pound of feathers... Same, see what I mean?
So if you have a servo that's rated for 250oz of torque it should be just fine. Keep the speed in the .15-.19 range (or faster) and you'll be happy.
I love analog servos, because they are cheaper and they don't put as much of a drain on the receiver pack. I had a Hitec 805 (analog) that would crush the Hitec 5745 (digital) that I use for my steering, the 805 was 40 bucks (U.S.) verses the $105 for the 5745.
Whatever you pick, make sure you keep them dry. They don't like puddles. I have smoked 4 5745's.