IOS – Which iOS versions are affected by the 2nd December date bug

(I'm not certain of this answer -- it's a somewhat educated hunch, based on using iPods for 10 years and Apple products for 25, and looking at wikipedia. If anyone knows from actual experience, use that answer instead.)

In general, I would guess that you can downgrade an iPod to the version of the OS that it was released with, but not earlier. So, for example, an iPod Touch 2g could probably be downgraded to iPhone OS 2.1, but not 1.1 (which wouldn't really matter since there was no App Store in 1.x!). Each iPod Touch gen-N ships with the N.1 release of iOS, about a month after the corresponding iPhone ships with the N.0 release.

An iPod Touch 2g should run all versions of iOS for the iPod Touch that have an App Store, though it doesn't support all the features of iOS 4. The hardware differences between iPod models might be a bigger issue for testing, e.g., older iPods don't have a built-in microphone.

My experience is no one, ten or even 50 apps can slow down your boot in any measurable manner. Even an old iPhone 3 with 11 pages of apps booted in visually the same time as a freshly restored iPhone 3.

The reason for this is a number of design choices that provide real benefits to the running system and also are good at isolating boot times from application influences. Specifically, nothing auto-launches, there are not multiple user accounts to prepare, and the OS systems that display and interact with apps work from databases that update when apps are deleted or installed - not at boot time.