As a couple people indicated previously (Dr. Bill, etc) the Scubapro S-Tek was bascially a Transpac 1. It is ok but lacks the stability with doubles that you get with a back plate.
The Scubapro X-Tek used a traditional backplate design and is a much better tech option.
Both used the same wings and the larger X/Tek, S/Tek wing is a carbon copy of the Dive Rite Rec Wing with all the positives (decent lift, can do an ok job with both singles and doubles and has a bungee to control the cell) and the negatives (taco's too much with a single tank, is a bit too narrow for doubles causing issues with pinching of the air cell and reduced with larger doubles, and has a bungee to control the aircell) of that wing.
In any event they were very short lived and were only cataloged for a couple years. They come up from time to time on e-bay, but you would be far better off with a backplate from any number of sources paired with what ever harness your instructor is comfrotable with and/or is consistent with your dive buddy(ies)'s configuration.
The Knighthawk is a back inflate BC but is not even what would be considered a cross over tech BC. It is too lightly constructed and the D-rings are not ideally placed nor heavily enough constructed for use with stage bottles, particularly 80's.
The Dacor Rig is a cross over BC but is way too complicated, is less than ideal for D-ring placement and it tends to shed nuts and bolts on a regular basis making it in my opinion, unsafe. The Genesis Recon is a slightly better choice but does not have interchangeable wings and the 75 lb wing that it comes with is overkill for some situations. You are also, like the Rig, stuck with fixed placement options for the shoulder and hip d-rings and you are stuck with the integrated weight system. And for a lot less than the cost of either one, you could get a really nice BP/wing setup.