The REACH of the zoom is greater meaning that you can put a more enlarged image on the sensor. That may sound like a good thing, but it is a pretty small part of the equation.
I dunno that I'd always go with the longest telephoto -- the quality of the lens involves more than just reach. Speed of the glass (as expressed in f/ratio) is a big factor. Don't forget that the effects of a longer lens on shake and sensitivity are generally negative too, even with optical stabilization and other features.
Fisheye and/or barrel distortion (as well as the related pin cushion) are trade offs with inexpensive glass -- for any focal length the truly high-end glass will do the best job of keeping images true to life.
http://www.mediachance.com/pbrush/help/barrel.html
The digital trend means that as sensor gets larger, with less noise, the ability to use digital enhancements to blow-up the desired portion of the image is greatly facilitated, though with a compact camera there are still some serious limitations to such enhancements in camera.
Of course the likelihood of using Photoshop (or similar) is something that you have to decide for yourself.
Your "rule of thumb" for the best "optical zoom" is still much more important for motion cams, as the amount of "post shoot" processing all but the hard core prosumers would ever do is just about nil...
Edited 2 time(s). Last edit at 10/06/2008 11:39AM by stan adams.