short runs yes, short time to heat exchange too - go figure.

Yeah, got to be a trade off between one and the other. I was going to say this before but as nobody's commented that the twin pass set up is "laggy", so obviously it's a good balance.
 
its all a question of what suits the application and flowrates etc.
higher flowrates and twin pass can become more pressure drop than others, but the cut off is unknown.
 
Will you be running it like a 225 IC set up (i.e. the pipe work in a similar position) as it would be good to replace that pipe i think for people running FMIC