Dale, what I've learned about steak is that the flavor we get, whether it be a gasser or charcoal, is mostly external (surface of the meat). The middle of the steak doesn't really take on BBQ flavor from our grill. But, just like pulled pork bark mixing with the internal meat, it imparts the flavor. When you cook a steak SV, you will get the absolute perfect med-rare, medium, or whatever you're looking for. Then, the method of the sear (hot charcoal, gas grill, cast iron pan) will impart the "flavor" you like, just as if you had cooked it there the whole time. It really does work. The great thing is, too, you can take tougher cuts (like sirloin) and SV them for 3-4 hours to tenderize them, but still have a perfect interior...time doesn't effect the internal temp, only tenderness!
Read all you can, in the Sous Vide section, and your learning curve will be less, with what a lot of us have already learned!