Unfortunately, I don't have time for a lengthy response. But I worked for a while at a high-end country club and we would occasionally Sous-Vide steak. This worked okay, but our idiot chef didn't sear them afterwards and they ended up flavorless. And I'm not sure about poaching, one of the absolute worst things you can do to beef is waterlog it, even surrounded by moisture, it will likely end up dry and tough. Such a small cut of meat won't do as well with a braise, and definitely won't function well in a poach. What you're describing is basically a single-serve braise on a small cut of meat. So you may be able to do it in a smaller amount of time if you sear it first, but otherwise you'll end up with a tough and dry cut of meat.
I'd agree that waterlogged steak is pretty much one of the worst abuses of beef you can manage. I was thinking that hopefully a few days of dry aging (not too long or else the enzymes will tenderize it too much) will stiffen up the steak a little so it doesn't absorb it all like a sponge. Additionally a smaller cut will mean less time in the water so hopefully less time to get all friendly with the moisture. Beef really benefits from dry heat and I certainly think it needs a sear before and possibly after. Even with all the potential difficulties I still believe it could be a very unique and delicious way to cook beef. Fingers crossed anyway.
Oh definitely give it a shot! I'd love to hear how it turns out. Like I said, I'm just wary about putting beef in water like that, but if you end up doing it, be sure to let me know what happens! You may want to try using beef stock with wine in it instead of brine, too.