No offense to your partner but if he telegraphs that easily he's not a good wrestler. By the time you see a good wrestlers shot, you're halfway on your back!
So true... I mean I don't have very good takedown defense, so I guess it doesn't mean much coming from me, but when it's a good wrestler I barely have time to blink. Timing a knee would be pretty damn tricky.
As for the actual topic, I am a big advocate of dropping a knee. You get so much more penetration (tee hee)on top of the added power and versatility for the finish.
I've never liked blast doubles. I prefer to turn the corner and lift. When your knee is on the ground you can stand up into the finish and run with it. You essentially have the power of your squat backing your finish. If your posture won't be as good if you didnt drop a knee, so you'll be using more back and less legs. This also makes doubles that came from a drop step harder to sprawl on, since the guy's back is straight and his base is sturdy.
But even more importantly, there's the versatility factor! From the knee you can do your typical lift finish, but its also incredibly easy to transition into an outside trip or to take his back as the situation requires.