I am pretty sure that the frames are the same except for steering geometry. I run an 04 rx with home made steering relocate measured to be the same as an apex. I also run an apex tunnel and skid on my original frame. It riveted directly together. Based on my experience pre mods, the weight of the sled regardles of skid and steering geometry is reliant on two things skid set up as addressed already and steering effort. The harder it is to steer the heavier it will feel. My suggestion is to be sure that the steering is in good order, such as bushings greased or oilites, be sure that the spindles are straight and well lubed. The stock spindles cases tend to bend and then bind on the spindle. Be sure to use cold weather grease. I like the Timbersled front end, because it gets rid of some of those issues. If the steering is good then go to work on the suspension adjustments. An rx can be made to handle the same as any apex. I swapped sleds on day with a friend to try his apex and had to chase him down to get my sled back. The whole setup is key.
Good Luck,
Jack