A matchbox in a MW Extra? No channels mixes in the Tx maybe? Anyway, sure, there's a weight savings and all that, but the trick is to get all the weight you possibly can out of the tail. My original MW Extra configuration needed noseweight with a Moki 1.8 in the nose. The Moki is a fairly heavy engine, though not as bad as some of the gas engine choices I've seen being advocated. Moving the servos out of the tail and yes, eliminating one of them by going to a Y pushrod for elevator, was a big factor in the airplane losing weight. Getting something like 4.5 oz of servos and wire out of the tail and replacing it with about .25 oz of a pushrod meant that about 11 oz could come out of the nose. So the airplane kept about 2 oz of the servo weight moved from the tail, but lost more than 13 oz overall just by moving the servos. The rest of the weight reduction was by getting the tail feathers MUCH lighter through replacing the "slab sta"b with a foam core thing etc.

So to answer the question about the bellcrank, since it's much heavier than the Y pushrod arrangement, you will pay for it through weight in the nose needed to balance properly.