The 8 bit custom value is probably the best choice. The custom value is the only effect that gives you the ability to send out specific values on the output channels without any rounding or conversion. 8 bit is all that's support on all of the lighting type output controllers. Any other type would be converted to 8 bit anyhow at the output controller module. (all current lighting protocols are 8 bit).

I don't think your problem is going to be on the sequence side.