lol....
The things that World Wind have as a problem over Keyhole was:
a) initial download size (180mb versus 30mb). Reason for the difference is that WW included the base globe imagery instead of serving it... the next version will be available w/o it and will let it be served to it, or, you can still download the default data with it.
b) CPU time: right now WW is a hog, even if running in the background; the beta version has fixed a lot of that so that it won't hog resources if you're not actively using it; as soon as 1.3.1.1 is replaced, that won't be an issue anymore.
c) I like the floating compass card, nice for a quick ref (I leave the lat/long data showing on WW, which includes a heading, but the visual is nice). Someone has added one as an add-on, though, so, I guess it shows you how much I care if I haven't added it yet.
d) Tiger data has to be added on, it's not already included
e) higher-res screen-captures. WW literally does a screen-capture; Keyhole has, in addition to the screen capture, a higher-res image generation (supposedly coming in WW later)
f) built in print functions
I didn't try the free version of Keyhole, I tried the $399 version.... like I said, the differences aren't serious enough to merit the price. I'll go back and try the free version once it's available again, and compare it against WW (which will always be free).
I still have to say, though, since I've gotten used to WW's mouse controls, I really prefer it over the way Keyhole's motion is controlled. And, I like WW's toggle buttons for flipping to topos or aerial photos or more detailed satellite images...
And, if you want something custom, you can do it in WW; and it might already have been done and downloadable....
I'll keep you posted as they both develop, see if anything significant changes....
-L