I have both the Halcyon with a 27lb wing Stainless,$450, and a Dive Rite Transpack 2 with Trek Wing,$450 with weight pockets.
Can't really add a Solid backplate to a Transpack. So it's soft on your back. If you're just using a thin suit or a tshirt with your gear it can be softer than a Halcyon. But my Halcyon has a pocket on the back that softens it up to. I use the Halcyon mostly with my drysuit and a weight belt. I have other backplates I use with doubles, 6 or 7 I lost count. Basicly I have way to much gear, not a bad thing is it. So I rotate the stuff. I like the Halcyon because it doesn't have a bunch of extra junk I don't need on it. I like the Trans Pack because it's soft and cushy.
And a backplate and wing is different. No extra junk hanging off and no extra buckles. Just the facts and what you need.
Oh, Wanna buy a new Aluminum Backplate and harness. $80 plus shipping. It's black and powder coated. Has new style Halcyon cutouts too. Like I said I have to much gear.
But I like and use both. The Transpack is nice in the pool with students too. I don't have any complaints on either the Dive Rite or the Halcyon.