The Sierra grip measures roughly 1.75" length wise from the backstrap of the grip to the receiver. On the trigger finger side (being a right handed shooter) there is a .40" shelf that your trigger finger will have to "wrap" around to reach the trigger. The total width of the "trigger finger" portion of the grip measures about 1.30".
Reach to the trigger measures about 2.5". Thats the measurement with the grip on the rifle, from the backstrap to the actual trigger face. Basically where the web of your hand is positioned on the grip to the trigger face.
Not familiar with the MIAD as I have never handled one. IIRC you can change the backstrap part of the MIAD to suit smaller hands or bigger. This gives you more options so you can determine what "feels" the best for your hands. Tho you probably won't change it after you find one suitable, so the rest of the pieces will probably be sitting and collecting dust.
I got the sierra grip from
sinclair international, go to "online catalog">>> "highpower equipment". They have it for $22.
hope that helps.
Edited to add: My hand from middle finger to the end of my palm is about 6.5". I have relatively small hands... i guess. ( I'm only like 5'4"- 5'5" roughly) LOL