meeka - for IMAC flyting - the 27 oz loading is just fine -on 1200 squares -
use an engine which will crank a 22x8 at least 6500 - you will be in good shape
for aggressive 3D crapola - lighte would be better -
we kep our 3D stuf that size - down in the low twenty's or high 19.
My 3D Petrol Petrel weighed 11 lbs was 1280 squares - ZDZ40 - very agile!