I got aperture at christmas, and I'm still learning to use it. The concept of when I am dealing with (or moving or deleting) a master file and when I am dealing with a version has been tough for me.
But, I think, aperture is saving me a lot of time, even on my old 17" powerbook (1.33ghv g4). It does bog down and spin at times, but it still saves me time overall. I do tend to take a lot of pictures of a good supject, and its way of stacking a series and letting you pick a compare image and letting you use it to find your one select, it really works for me.
I also really love the backup vaults. Really really. My laptop died for a couple days on my last trip, flaky power on the boat, I think, but I was totally backed up when it died, thanks to aperture. I lost no sleep.
On a trip, I do very minimal culling. I just don't spend the time on it. On my last trip, I was shooting a couple hundred shots a day, 5mp raw images, 4 or 5 gigs a day, deleting almost nothing. Really only images that were completely dark or obviously out of focus. I'm on vacation, I'd rather be in the water, napping, or eating, or even interacting with other humans on the trip. And with my laptop dead for a few days, I didn't even manage to do that much culling, I just copied them off onto a hard drive using my wife's laptop and kept shooting. So I came home with, I think, around 30 GB of files.
I often have 10 or 20 shots of the same subject, and I find it very slow to pick the best single shot. That's why I wait until I get home to do my selecting. They typically aren't experiments, they typically have all the same exposure. I'm looking for the one with just the righ composition, depth of field, and gesture.
I complely agree with you that I'm going to end up with just a gig or two, but the way I shoot, the way I take time over my selects, and the way I fill my time on vacations, it just takes longer for me. Different strokes....