+1 chain shirt is better than +2 hide ANYWAY you look at it. Whether you include the Rhino ability or not doesn't matter. It's just b/c of the nature of Chain shirt as a superior armour... better ac bonus, same max dex, better ACP, light armour instead of Medium...
It has nothing to do with the "Rhino" ability at all, just the fact that (As I stated above) Chain shirt is superior in ALL aspects except it costs 85 GP more at the Base price.. but once you get to magic that ceases to matter. Lets do a little comparison:
+1 chain shirt is:
1,250 GP, AC: +5, Max dex +4, ACP -1, Light Armour, 25 LBs
+2 Hide armour is:
2,165 GP, AC: +5, Max dex +4, ACP -2, Medium Armour, 25 Lbs.
Hmm.. BETTER price, SAME AC, SAME max dex, BETTER ACP, LIGHTER armour, SAME Weight.
So again I ask you... Does the "Rhino" part actually matter in this case? nope.
Hide just plain sucks..