The root of the 10.5 vs. 12.9 for multitasking issue is the fact that on the 10.5, each window will display the "compact" version of the app (as it would appear on an iPhone), whereas on the 12.9, each window will display the "regular" version of the app (as it would appear on a 9.7 iPad).
Same here. I quite enjoy my 10.5. I started with the 12.9. Switched to the 9.7, and now I’m riding into the sunset with this 10.5. Right in the middle with size/portability. Apps still work the same in my experience. They just look a little different in split.
Good! But while it is not an issue for many, it will be for some, and so it is important for people know what the differences are between multitasking on the 10.5 vs. 12.9 so that they can make an informed decision.
OP said there was no apple store nearby and then turned around and said s/he was going to an Apple store or Best Buy. Hopefully there is in fact one close by. Anyway, I mention that in order to say I would recommend before refunding anything to get OP’s hands on a 12.9...whether that be in store or from a friend. Play with it. Try to do some daily tasks. If it “feels” better then look at options for returns/swaps or what have you. iPad has only been out since the 13th, so OP has at minimum another 6 days before the opportunity door closes.