I have a track only car (tune on the street but do not daily drive or anything) and I am currently pretty happy with the maps but have been running with EGO controller step size at 0.

Is there any real reason for me to turn EGO correction on?

 

I don't think you'll be in EGO correction territory a lot on the track where it matters so either way is fine.

 

you can run 100% closed loop...so your entire territory is EGO territory.

It could be useful as temps increase, or any other variable. I don't really see any reason not to.

 

I assume engine management goes to open loop at higher loads because WBO2 sensors cannot react fast enough nor accurately?

 

It can if you tell it to.

Under More Settings -> Lambda AFR you can define an upper switchpoint (in kPa) at which a different limit is applied to EGO Authority. This limit can be made zero if you wish.