multiple O2 sensors

[Dave Williams]

-> can't help much (it does help some) either way.  Exhaust temp is just
-> fine, actually better.

 I find the thermocouple response on my EGT to be fairly fast; since
you'd just use it as a trim to the final AFR I don't see that it has to
be "instantaneous" like an O2 sensor.

 I have looked longingly at some of those IR sensors though.  Makes me
wonder how fast the outside of the header tube responds to exhaust
temp... but it'd be influenced by ambient temp, air flow, etc.