I've only had Tweetie 2 for a couple of weeks and it's trained me as well. Every program that 'rubber band' effect now has me trying that to refresh content.
I wouldn't be surprised to see other programs stealing this idea soon. It's really brilliant.
And yes, I double-tap real spacebars every now and then as well.
I do too! I wish Apple could implant something like that into their software. I think it would be so much easier. I was typing an email up on my MBP yesterday and by time i finished it to reread it it was a disaster, I kept hitting the space double... oops....