Except the TBR isn't waterproof but rather "weatherproof"=deal breaker for me over the vortex which is waterproof.
The Vortex website says nothing about being "submersible". It says "O-ring seals prevent moisture, dust, and debris from getting inside for withstanding harsh weather conditions". That would leave me to believe the Vortex is actually "weather proof" just like the Leupold. They are so close speck wise, I'll bet they come out of the same Chinese factory. Street price is nearly the same too. I think the only real difference would be long term service, as I doubt Leupold is going anywhere soon. However, at the rate this technology is improving, by the time you wear one of these out you'll probably want a new one anyway.