Well, becuase I want dual elevator (not single), BUT, there's no reason to have 4 oz of weight in the tail if I don't have to. If I can use 2 servos equaling 2oz total, and total torque and speed is still 120 then why not??

I personally do not think a single 5485hb would be enough, 2 would weigh over 3 oz, and they are .20 sec (much slower). they are also not metal geared. So 2 of the 5245mgs seem to be superior in everyway except price