On a model of this size and expense it should be a crime to put a reversing Y in it to control the elevators, these crash WAY to many models IME, loose it quick.

The Smart-Fly Equalizer is the best bargain if your using the Eclipse. The next best solution is to use Hitec digitals and have one reversed so the move in unison. The last option is to get a transmitter that will do the mixing in the radios programming like a Futaba 9C or a JR 9303. Strangely enough the newer Hitec Optic 6 channel has a dual elevator mix that would solve your problem as well, sort of a step backward but it does have the feature. I have an Eclipse and this is the exact reason I bought a Futaba 9C so that I didn't have to go through this hassle ever again. Strangely enough I learned that having the dual elevator mix wasn't as desireable as I had at first imagined it would be. It seems there is a slight lag between the two servos throughout their arc of travel that results from the mix itself, go figure! I'm now using a heavy duty Y harness with Hitec digitals and sync them together with the Hitec programmer which produces a PERFECT syncronization of the two. As far as I'm concerned it's the best way to do it....IF your using the Hitec digitals anyway.

FWIW getting the elevators to track in syc ACROSS the range of full travel is next to impossible if one servo arm is pointing up and the other is down. The problem is more pronounced if the throws are big like 45 degrees for 3D.

With the airfoiled tail surfaces that the WH planes have ANY mismatch will show up in flight and it will make getting the plane to fly in trim next to impossible. These surfaces are VERY effective and are nothing like flat tails on smaller models. I learned this the hard way and once I got them tracking together I was amazed at how straight the plane flew and how much easier it was to fly certain maneuvers, up to that point I had been fighting the plane without realizing it.

My money would go for the Smart Fly Equalizer 2. Get one, put it in and adjust the elevator halves to track each other as closely as possible. You CAN NOT eyeball this BTW! Make a pair of 1 foot long pointers with some .070 carbon fiber rod and a pair of clothespins, CA the rods to the clothespins then clip them on to the elevators. Next bring the tips of the rods close together behind the rudder and then work the elevator through it's range of travel with the radio, they should track each other exactly the same all the way from top to bottom, if not adjust the servos or Equalizer till they do. One last point is to be sure that when your servos are at neutral and holding the elevator centered it's a good idea to use and incidence meter to verify zero degrees on BOTH elevators, remember that none of this will do you much good unless the elevator halves are matched at center as well.