He doesn't have to not be bangin 'em in to properly gauge his talent. As I said several times in this thread, he did well to pick the ball out of the air several times yesterday but then conceded the ball far too easily, and often just as the midfield was arriving to support and we were hence more stretched out as a result. It doesn't take a worldie to hold on to the ball for at least 10-15 seconds longer than he did and give your side a chance to create a rigid shape in preparation for scrappy last 20 minutes home side attacking play.
I agree that he was somewhat careless with the ball and doesn't have pace but the way I saw it (not the best view in the house, I grant you) was that he lost it a few times but it was just as often a misunderstanding between him and another. He played a perfect ball forward beyond the full back when Lennon was still making his decision as to whether or not to run. Lennon got a bit pissed off with him at the time but I maintain that Kane did the right thing there: Lennon should have made the run purely because he would outpace the full back and because there was better, safer time-wasting potential (and maybe a goal to seal it) at the United end of the pitch.
Long story short - those who are saying that the loan periods don't always work need to consider the player in question. What I've seen of Townsend so far is that he is a great athlete and wants to make it work for him - but I doubt he'll necessarily gel well with a team. Kane looks like he has a real brain on him and a lack of pace isn't going to stop him from succeeding. What made Townsend look good on loan is his clear physical ability over the competition (and his own team-mates) while, if Kane needs players to move around him and lose their markers (or to get him the ball in a certain area) he can't really be judged fairly on the basis of that.
I suspect that, if Defoe goes, Kane may be enough of a third striker to offer a different option to both Soldado and Adebayor.