@neurostar: "In theory, driving power LEDs in parallel is a bad idea." The design being worked from the first page of the thread had current limit resistors in each string, thus they are not actually in parallel.
@charliehorse,
This design is total overkil for a limited use stage lighting setup. Running left & right lights with brightness matching controlled by PWM adjust from ardiuno would have been plenty. Logic level mosfets with 0.005 Rds and 350mA going thru them would dissipate <2mW and would have no cooling needs.
Now you have a ton more parts to deal with, you've got a pile of NPN transistors that may need cooling as well, dissipating 250mW each, a controller that you are using at 100% capacity, no derating, and with 0.95mm lead spacing which will be a bear to solder hand.