FYI, double check w/Crow's Tactical. Last I spoke with Danny, he was either not carrying SOTech any more or was thinking about stopping. OPTactical is currently deployed (or about to be), though he's got some folks helping/running the operations.
I've tried 5 times to get SOTech as a product line. 5 times I've called/emailed/etc., always receiving a "we'll get a dealer pack out right away" and then....nothing. I finally gave up.
The Callahan is a nice rig from all reports I've read. If you want to be able to separate the plate carrier and carry only a Hellcat, it's the bomb in versatility. If you're always going to wear the plate pockets, there are also alternatives from High Speed Gear in the Wasatch (12 mags) and Weesatch (8 mags).
Raith...if you're looking for REAL plates, I sell them. Figure about $240 each for Level IV ceramic plates.