Final comparisons of render speed will be useful to know.  Just make sure that they are all done on the same system, with the same file types, and the precisely same export settings.

However, you can export plenty of disc or file content overnight on an ancient core 2 duo, perhaps with little or no difference in the electric bill.

Some things consume lots of time before reaching the export stage. 

More than anything else, though, I'd be curious to know how AS and PS15 compare in terms of:

1. Allowable length of an AVCHD timeline before scrubber navigation or preview become sluggish or the audio gets out of sync,
2. Stability and speed of background render operations involving overlays, effects, or transitions.
3. Incidence of export errors when creating files or discc images.
4. When an export error occurs, whether AS provides the problem frame's number in both export to file and disc image; in the case of PS 12.1, you get that information when exporting to file, but not when exporting to disc, which makes trouble-shooting more difficult.

Working with a Sandybridge system and AVCHD, is it possible to alter clips, add effects, or create title overlays as smoothly as to shuffle and deal cards?   At what point can one bungle and incur a "hang"?  Are PS and AS significantly different in this regard. 

One simple, standard test might be to compare the time required to background render a single heavy-duty effect on one AVCHD clip.  It might be something like a color correction, speed, or rotation.  The next test would be to see whether the time required for that same effect changes if the altered clip is somewhere on a 60 minute timeline of AVCHD content.  The final "Russian Roulette" test would be to test how many clips you could apply the same effect before the background rendering becomes slow, stops, or a hang occurs.  A fast system probably helps, but are the efficiencies of PS and AS significantly different too?

Next mystery: how to edit AVCHD on a 2-core tablet with 1 GB RAM.  I imagine it's impossible, unless the timeline is very short.  Tegra 3 or iPad3 devices may make it more feasible, but most people who use the apps may be interested only in low bitrate phone video.  How, in heaven, some will be able to work with 1920x1080 content will be a feat to behold.