Hi Andy, I have a similar dilema - I joined ADAA 2 years ago and am looking to supplement with either Aberdeenshire Roving or a specific upriver beat !
The ADAA water is really good and as you say Sunday fishing for trout unlike the Cooncil - some Sunday's I have had the beats to myself, but Upper Parkhill/Lower Fintry can be busy when the Rushdies are running (not Sunday's though).
Big disadvantage for you will be that it will (initially) be unfamiliar water, but then again that is also fun too ! As you live in Dyce the Shire beats are close by so that is not a problem......but if I lived in Dyce you'd have to prise me away from the ADAA beats !
I used to have a shire roving ticket (for a few seasons) in the late 90's early 00's - it was great value, great water but in my opinion for me living in south Aberdeen the ADAA water is stupendous value for money (for me as I fish ALL the time) !
Worth pointing out that ADAA does an an exchage with Inverurie so that beat you'd get as well as left bank for some of Kintore (though not the bit round the Golf Course/Clubhouse).
Good luck with your decision !
Cheers,
Lindsay