After my first takeoff at 2700 lbs, DA= 200' and saw steady 1500 fpm climb rate which was more than double the 172, I figured it would not be a problem on a hot summer day in Leadville, Co. I was off easily in 1000' or so.
Have just been reading a draft publication from CASA and on page 21 there are some rule of thumb guides for multiplying factors that can be applied to the Vans ISA numbers.