da Rock

There actually isn't any compelling reason at all to use any particular size servo over any other. The only really important consideration that matters is what was just mentioned, how hard is it to move the pushrod when it's connected to the carb.

Once upon a time, mini servos were a new deal and cost more than standard ones. There certainly isn't a good reason to use a more expensive servo even if it'll do the job and you don't need to save weight. So there wasn't much reason for anyone to suggest it back then. And right now, almost nobody seems to worry with the idea because, except for the lightly powered wet models and the electrics, there isn't a compelling reason.

But if you read a lot of magazine articles about models that were plan built or kits, back before the magazines went almost entirely to ARF reviews, you did see some authors/designers mention using lighter servos for the task to save weight. But they didn't make a big deal about it.

And with the bigger models that're the rage these days, weight means little to most. And truth is, the idea to use a heavy throttle servo is just as useful to balancing most models if you're smart enough to ignore the designed location on the servo tray (that's most often behind the CG) and move the sucker up front, nearer the engine and in front of the CG. Since getting back into the hobby, I've stuck together 5 ARFs, and every one had the throttle servo back on the tray with the rest and the tray behind the CG. I put that servo just in front of the CG on all of them, and every one was lighter for it.

Nowadays, with ARFs being what a bunch of the flyers have flown since they started, nobody even seems to think about such an idea as using one lighter than the rest. Well, except a few of the sharper electric writers. But then, most of the electrics are using ALL micros. And probably fewer still would think of putting a servo somewhere other than where the ARF designer has it.

Hey, your idea is sensible and solid. It just isn't widely thought of. And with mini's as cheap as standards, and some cheap BIG dudes out there, it just makes good sense to use what does what needs to be done. Mini's will drive any throttle I've ever seen that didn't have a poorly installed or designed connection system and a maxi in a big dude that's probably going to come out tail heavy can help you solve that CG with less added dead weight.