Just an update, for those of you in the same boat.
We are still bouncing, but I changed our routine up to try and start cutting it out. I moved from bouncing in front of the computer to bouncing in the dark bedroom at bedtime. I am also laying him down sooner, when his eyes are closed, but before he's totally out, he's usually still humming or twiddling when we go lay down on the bed. For naps I've stayed at the computer, I figure it's light in the bedroom then too anyway. I am making sure I lay him down before he's comatose though, instead of trying to finish the thread I'm reading! For my sanity and patience, I had dh take over the last step of the bedtime routine before the bounce (reading books) so I can have a couple minutes to center myself and prepare so I'm not so easily frustrated if he takes a long time to go out. During this time, I grab my ipod, set it to play a good audio book or some podcasts quietly, and string the earbuds under my shirt in the back. I clip my player to my back waistband. DS loves to play with my ipod, but if I'm sneaky about it like this, and only put one earbud in after the lights have gone out and he can't see, then he doesn't notice it's there. It really helps to have a little something to entertain me.
Since I'm laying him down before he's hard asleep, I expect to have to nurse him in the bed some before I can leave. There have been a couple times I haven't had to, to my delight. I tried laying him down earlier a couple of months ago, and it didn't work at all then! He would be so sleepy, I'd lay him down and nurse him, and he'd get all frustrated and wake himself up and then I'd have to bounce him again for 3 times as long as he normally needed. The only things that are different this time is that he's not quite so sleep starved since I've gotten him on a more consistent bed and wake time, and that I'm bouncing in the bedroom, so there isn't as much travel needed to get him into the bed.
The other thing that I've changed about our routine is that I have started unlatching him sooner while he is falling asleep. I've been using the Pantley Pull Off method to get him to not need to nurse while he is asleep for a long time, but I hadn't pushed the unlatch sooner for a while. My new general rule is, once he takes 3 slow sleepy breaths in a row without suckling at all I unlatch. If he stirs and reaches out for the nipple I relatch him, but as soon as he does 3 breaths together we unlatch. He's adjusted to it well, and will sometimes unlatch himself now when he's ready to settle all the way to sleep. I don't unlatch him while we're on the ball, only after I've laid him down in the bed.
It's been a couple of weeks, and DS has slept a 3 or 4 hour stretch at the beginning of the night almost every night since we started! There have even been one or two nights that he's only woken up twice the whole night! It's a huge step forward for us. Last night dh and I had a nice leisurely valentine's dessert and uh, celebration , and I didn't have to run to settle ds again once! He's also not usually waking up in the middle of his nap anymore either.
I think I'll push up our unlatch again in a couple of weeks, as a step toward night weaning and hopefully even more sleep. As for the bouncing, for now I think I'm happy to have it as it is. I may try and slowly cut down the time we spend on the ball, it's usually about 20 minutes now, but I'm so excited to have things so much better, I almost don't feel the need to push it right now. Good luck to all!