>ISTR using a 4000 a couple of times, my impression is the Elite is somewhat more "split". Do you find you use the extra keys/functions the 4000 has vs. a standard keyboard like the Elite?

With the Elite I HATE the arrow buttons layout. The arrow buttons should be an inverted T layout not a + layout (IMO)

I actually only use 3 of the extra dozen or so buttons on the 4000! Volume +/- and the Calculator button. The shortcut to the Calculator is especially fantastic.

My favorite natural keyboard was actually this one (but I can't find it to buy it anymore):
http://cdn.hometheaterforum.com/6/68/683857ab_htf_imgcache_43123.jpeg

Notice the double height delete button.

With the one I use now:
http://www.microsoft.com/hardware/mouseandkeyboard/images/products/nek4k/mk_productfeatures_nek4k.jpg

The delete key is only single height and directly above the Delete key is the Insert key which I accidentally turn on a few times a day... very annoying.