Inconsistent shifting: any ideas?

Something I just noticed, listening to the engine in the videos - the 2nd run, (first video in the thread), which had the tightest 1-2 shift, is also happening a few hundred RPM lower than the others. So I either shifted below 5500, or in the other runs I'm shifting over 5500. Anyway, they're not the same.

Does RPM affect shift firmness?