My new double-bass pedal arrived on Friday. After the LAN party Friday night, I couldn't wait and opened it up and tried it out (quietly) at 1:00 a.m. Over the weekend I had a few chances to actually play out more and break it in a bit. All I can say is that my left leg is sore today :) Imagine that since you were 13 you've known how to ride a bike, but the only bike you've ever ridden only has a pedal on the right side. Now you get a new bike and it has pedals on both sides. It's not completely foreign to me, but when I attempt to try some fast or more complex licks, my left foot and leg just can't keep up.
Another detail I'm trying to get used to is the pedaling technique with double-bass. I've always played so that the bass drum beater strikes the head and then rebounds off, leaving the head to resonate fully and get a punchier sound. But double bass is a different story. In order to play with both legs, I have to sit closer to the kit, and as a result there is more downward force on the pedals (rather than sitting farther away with my leg stretched out a little bit). This makes it nearly impossible to allow the beaters to rebound off the head and instead are buried into it with each stroke.
There's nothing wrong with burying the beaters. Many, many drummers do it. It's just a weird feel for me because I've never done it. One point of compensation though is that I have to tune my bass drum header lower so that it is looser. If it's too tight, the beater rebounds naturally from the tension in the head, but the weight of my foot tries to bury it and there's actually a little bit of a double-stroke or extra "tap".
I also need to play around with all of the settings, such as the pedal tension and beater angles. I'm used to playing with a lot of tension and more angle so that the beater can really slam into the head for a strong sound. However I don't think that type of setup will work very well for fast, repetitive patterns. Neither my left OR my right foot will be able to keep up.
It'll take some practice and tweaking, but I'm really enjoying it so far.