This is exactly my problem. I have an iPad 2. I know that if I move off iOS5 I have to move to iOS7, which really wasn't designed with the iPad 2 in mind.

I'm now stuck between a rock and a hard place. Stay where I am and many apps (like Spotify which I pay for) no longer work, or upgrade to iOS7 and know that the iPad 2 just isn't powerful to run it in the same way in runs iOS5 (for which it was designed for).

I'm desperately waiting for a jailbreak so I can install iOS6, which I see as a half way house.

The reality is that Apple are deliberately degrading older devices, in order to make them obsolete. Of course I understand they are just building software that is designed to run on the most current and powerful of their devices, but the deliberate prevention of installs of older iOS versions when a user specifically wants it is frustrating.

In hindsight I shouldn't have bought an iPad, but there wasn't a viable alternative at the time.

I'd tend to disagree with your assessment of iOS' performance on the iPad 2. I have an iPad Air and an iPad 2 and quite frankly the iPad 2 crashes less and runs more consistently on iOS 7, as opposed to my Air. It feels as though iOS 7 wasn't ready for the Air, but it has been improving with each update.