The time-stretching way is the way to go for what you're trying to accomplish.
Let me explain a little bit of what's going on under the hood so that you can understand why:
After Effects thinks primarily in time (seconds) not frames. A composition that is at 30 frames per second will sample the image data from its layers 30 times every second. Similarly, a render item that is at 15 frames per second will sample from a composition 15 times per second.
So, it's not as if After Effects is holding a bunch of frames that then get distributed across time (which is kind of what you're thinking of, it seems).
There's lots of information about frame rate here:
Thanks. I guess I was hoping you would say look here for the "work the way Ocean wants" button, but I guess I'll settle for someone confirming my wild theories and functional work arounds.
Appreciate the help.
While we're not on the subject, is there anyway to set an offset in 'syncronizing nested comps'? Mostly it seems to work pretty well, but sometimes they get off from each other and it is muy annoying. I think it has to do with time remapping, or having multiple copys of a nested comp which start at different times. IIs there anyway to say, look at this layer as the one to snyc times on?
It's actually the same issue that Todd already described - your time-remapping needs to be frame-exact to use consistent results. If there is a minor sub-frame discrepancy because AE works on "real" time, this may result in the wrong frame being sampled. The longer the clip, the more such tiny discrepancies will accumulate and manifest themselves. So in short, you may actually sometimes need to use seemingly odd values to get correct alignment. To make this easier, you may wish to toggle the time readout to frames by simply Ctrl+clicking on it. Also keep in mind, that inputs accept simple math, so you may use frames*frameDuration as the input format, i.e. 50*0.04 will give exactly 2 seconds in a 25 fps PAL project...