Xecuter 2.6 chipped v1.6 Xbox with WD320GB SATA + adapter/80wire cable. AID installed UnleashX v572 main dash and, for this test, using the Default blue skin*. The C:\drive has about 324MB and E:\drive about 1GB of free space:-
Cold boot: 22.31 secs
Reset: 15.52 secs
Boot XBMC as an App: 10.38 secs
Restart UnleashX main dash from XBMC Shutdown menu: 16.06 secs
IGR (from TimeSplitter FP): <17.28 secs.
Very difficult to IGR and press stopwatch button at the same time
so it is actually very similar to the XBMC boot time ie. around 16 secs.
I'm happy with these times although I know for sure that my previous HDD used with the same Xbox, a 120GB Seagate IDE, booted everything much faster with a standard 40 wire cable and really not that much less content.
* what skin you use is important as some have intro FMV and/or loading screens which extend the boot and reboot.
I've just done a new test on my most virgin Xbox a v1.2 LE Green still unopened and therefore with standard Seagate 8 -10GB IDE HDD. Softmodded with SID/AID, 327MB free on the C:\drive and 1.5GB free on the E:\drive. All other criteria the same as for the chipped machine:-
Cold boot: 18.76 secs
Reboot: 13.40 secs
Boot XBMC as an App: 6.32 secs
Restart UnleashX main dash from XBMC Shutdown menu: 17.40 secs
IGR (from TimeSplitter FP): <17.40 secs.
So not that much difference except for that XBMC time but that might well be because on this machine (limited E:\drive space) I've kept XBMC very light ie. minimal skins etc. That really demonstrates that hardware is really not the main factor in determining boot times.