Hoping someone can give me some advice regarding my older iPad2 (32GBG model and has the bigger connector, not the lightning connector, so can't run Siri etc) and iOS versions.

My iPad2 still uses iOS 6.1.3 (not jail broken or anything) but increasingly I find new apps need at least iOS7. I can't upgrade to iOS7 (which I believe would work fine on this model) as the next step is to install iOS 8.4.1.

I constantly read a mix of results from people having upgraded to iOS8, and the general consensus is that iOS8 is problematic on the iPad2. The latest version iOS8.4.1 seems to have addresses some of those issues but my question is - should I upgrade as it is a one way step - I can't go back once done. And once I have iOS8.4.1 on my machine, will I be offered a further upgrade to iOS9? And if so, should I upgrade to iOS9?

So, I am in a dilemma - I want to be able to install and play with newer apps, but cant without upgrading, and if I upgrade, then my machine might be unbearable awful.
I am a very light user, just play about with different apps, but the main use is web browsing, streaming videos from the Internet, Skype, and reading the NZHerald app. I want to put Chromecast on the iPad so as to be able to see the screen and sound duplicated on my TV, but need at least iOS7 to do this.

Has anyone upgraded an older iPad2 to iOS 8.4.1 or iOS9 and how did your machine perform? Do you regret upgrading?