Back to the original question.. Are SOG fixed blades practical? I guess that depends on what you do for a living. In regards to the specific knives you mention i.e. the SOG Tech Bowie and the SOG Agency, if you frequently go behind enemy lines and are discretely remove sentries then yes, they are great knives. But lets not kid ourselves, they are collector pieces that are fun to fondle. 99.99% of the buyers for these knives will never leave the couch. In this respect some of the arguments against the agency like steel type are silly.. AUS8 will dispatch a sentry just as well as A2.
The nice thing about SOG is that they make a large range of knives from historical wall hangers with limited use (Agency) to tough beaters that you can use and abuse (Northwest Ranger or the Force). In addition, they make them available at differing price points for most budgets. For true "operator" types they even make knives like the SEAL Team Elite that are tough, functional, tested, and durable.
Some of the comments in this thread make me think some of you guys either can't see the forest for the trees or have no sense of humor.