If you want max performance from th flat foam -in a "pattern" type flying - use 6mm foam for stiffness
the Shock flyer type stuff is for adventure flying
The FAI Shock Flier is prety good in dead calm with GOOD servos and proper hinging and linkage but this is not what these models were intended for.
we have gone thru easily-- 100 small foam models this year -(Guy and I) of all types from 4 ounce all up to 20 ounce all up - sort of a "crash" program .