Felipe, the Halcyon Infinity system has the Cinch system, which is a releasing mechanism for the shoulder straps. It also comes with strap padding and a back pad, neither of which are really necessary. Halcyon makes very good gear that sits at a premium price point, but at least they have been in the backplate and wing business since the beginning, which ScubaPro has not.
A friend of ours bought the ScubaPro X-Tek single tank setup, because he gets key man pricing on SP, so I have had a chance to help him set it up, and to see the gear and handle it myself. I honestly wasn't impressed with the quality of the workmanship -- if you compare the appearance of the gear with DSS or Halcyon, it just looks cheaper. I'm talking about the stitching on the wing, and how the grommets are put in -- things like that. But if you buy their stuff, make SURE you don't go for the oversized wing they want to see for a single tank setup. The small doughnut wing they sell is reasonable in size.
If I were you, I'd buy something less expensive than the MK25/S600s. I have them as my doubles regs, and they're great regs, but they're expensive to service, and they're expensive to buy. For single tank diving, if you want to stay with a major name brand, something like the Aqualung Titan is a much better purchase.
I don't want to discourage you from buying gear from your dive shop, but remember their goal is to put you into the highest profit margin equipment they sell. And when you get into things like backplates, unless the shop where you are looking has a significant proportion of backplate users, they may not know what they are talking about. We finally talked the LDS for which Peter and I teach into carrying backplates . . . but we're the ones who sell them, and we still have to go into the shop and help folks who buy them to set them up.