The one time I made steaks sous-vide there was no lack of flavor. Does "conventional" mean grilling?
A couple of schools of thought in the steak world: "smoke and char flavors from the grill are essential to steak" and "smoke and char flavors from the grill detract from the steak." I think the varying quality of the meat has a lot to do with this. I belong to the second school, but my circumstances can't be divorced from this. I live in one of the few spots in the country where prime, dry aged beef is available retail, and I consider steak a special treat ... something to have every couple of months, and a reasonable excuse to destroy the food budget.
If either of these circumstances were different, I'd be buying less flavorful meat, an my prefered method would probably be the grill.
If not sous-vide, my favorite method for top quality steak is the stovetop. I've had plenty of good luck with both high/low temperature confentional sauteeing, and with the slow and steady Ducasse method. It's possible that both these methods give the meat enough time on the heat to infuse some smoke from the fat in the pan to infuse the meat. I don't know.
One thing I'd like to improve with my sous-vide method is the char. I would like to go a little longer, perhas on a less hot pan (relying more on time and maillard-enhancing ingredients) and to use enough oil to concuct heat deeper into the surface irregularities of the meat.
I don't know if a pre-sear would be worth it or not. It takes a lot more time and energy to sear a cold piece of meat; so it's more challenging to keep the heat just to the surface.