The first "truth" to consider is that "gaited horse saddles" are a marketing ploy, not an operational description. All horses need saddles that fit. The claim that "gaited" horses need more "shoulder room" than trotters (the most common justification) is called into question if you watch one or two runs of the cross country course during the Rolex or Spruce Meadows. Take a peek and you'll see why!
The Imus products have a very sketcty reputation. If you must have a "gaited horse saddle" Stubben makes one. You'll get Stubben quality, but you'll pay a Stubben price.
The other thing about "gaited horse saddles" is that most will put you in a "chair seat" (a/k/a riding a la brida
). This is not necessarily bad for short periods, but is very hard on the horse's back. It virtually guarantees that horse is traveling ventroflexed. Again, for short periods this can work. Over long periods it guarantees a sore back.
So find a saddle that fits and does not force you into some specific seat. A "balanced" or "centered riding" seat works very well with horses (gaited or trotter) and allows the rider the freedom to choose the way of going at any given time.
Good luck in your search.