ive worn the adrenaline for different reason than being flat footed (have weak ankles, although they are getting better) but ive worked at a running store and have seen lots of people run, now i am also no doctor, but... i always advised against insoles in shoes such as the adrenaline as they are already really supportive shoes, unless they are custom orthotics prescribed by a doctor. (i trust the doctor has a clue what he is doing, although ive had different experiences with PTs...) the biggest difference you will feel between the brooks and the asics is the asics will be much softer plushier ride, while the saucony will be more comparable to the ravenna with a little snugger fit especially in the toe box. (both really good shoes, i personally prefer the saucony guide over the asics) hope this kinda answers the question...
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