Bert,
I think Win 8 starts up faster on head to head comparisons on some machines, especially from sleep. I have an ASUS Slate EP121 touchscreen tablet (i5 CPU, SSD) that ran Win 7 Pro, upgraded to Win 8 Pro. The wake time (if the tablet has been in sleep mode) is appreciably faster, down from over 10 seconds to literally instantaneous. I don't know if this is the result of Win 8 allowing a "connected standby" mode, like a cellphone (I had only heard of this being implemented in Win 8 for ARM devices).
A cold boot is still about 15-20 seconds. This is rarely an issue with Win 8 computers however, since the concept is never to turn them off (it is even hard to find the shut down command on the new "Charms" bar).
Not withstanding the startup time, IMHO there isn't much to gain install Win 8 on a desktop, since all the productivity advantages are for touchscreens, the mouse/keyboard commands are actually not as easy to use as Win 7.
