Looking into this I discovered a new use from my MacBook Air 2nd gen: XCode can download and run old versions of iOS (min is 8.1 - so not all iOS versions) on pretty much any iPhone/iPad that I can think of.
That said, I can get no dev tools working with, say, iOS9. I get the ipad, starts fine, open safari, load a page. Then I go to the dev menu on the mac, choose the ipad emulator where I can see my tab, click on it and I get the web inspector: Only three tabs show up, Sources, Console, Search, and no matter what I do I cannot interact with the page at all. Console doesn't let me do anything and shows nothing, Sources is empty and Search doesn't find anything.
Did you have any luck with this?