I have a Trifecta and it is a great pad though I found it not to be the best for my sore-backed horse. I have used an Ecogold and liked it a lot but I don’t own one.
I have a horse that does get a sore back and he likes 3 pads: an Ogilvy, though to me this pad is thick and it is not my favorite. You have to have space for it under the saddle to even contemplate it. If it tightens up the saddle fit it obviously can make it all worse. A Supracor: great pad and super cushioning. This pad really, truly has fixed two sore backs for me. It’s SUPER. but also thick, see above re tightness. and it’s not my go-to everyday pad, more a therapeutic pad because it raises where the rider sits which I don’t love. And my new favorite, the Invictus pad with pockets for shims. this is the one I am using every day on my horse that gets a sore back for maintenance (with no shims), and on my other horse who doesn’t have a bad back but who just needs the shims in to make my Tad Coffin fit him perfectly as he’s petite and the TC is just a bit wide without it.
It’s awesome. I love the chocolate color too, it is so discreet. Here’s a pic with ALL the shims in (2 sets front and back) (ignore the pudgy post-winter Tiny TB’s disheveled state please, didn’t clip him this year, he hasn’t shedded out and looks like he has a pot belly, and he is yawning! fordtraktor camera fail): https://fordtraktor.shutterfly.com/pictures/176
Even with all the shims it is still very sleek. but it provides enough lift to keep the saddle nicely off his spine and he sweats beautifully and palpates perfectly under the TC. he also is moving better than he ever has with more lift through his back and more willingness to stretch and bend to the right. it’s great. Part of that is the SmartRide saddle I am sure, but before he had a custom fitted wool flocked saddle so it’s not like he has ever been ridden in a poor fitting saddle since I’ve had him. The combination of the two has really improved him this year in the back department. It certainly isn’t fitness because he’s dreadfully out of shape and I’ve been riding very inconsistently this spring, have been super busy with a few work projects. See pot belly.
Also the Invictus pad doesn’t make you feel like you are sitting way above your horse like the Ogilvy, Supracor or, the worst, those old Beval Therapeutic pads. remember those…? OMG, teeter-totter! 
That said, I still do like the Trifecta and use it under my dressage saddle – that’s still a nice choice!