UBB.threads PHP Forum Software Community Forums General Suggestions and Feedback Google still not there

This is in another thread Update Robot Txt 7.3

I think this Topic would be handier to continue the questions
as its covered a hell of a lot about Google and listing ect..

With 7.3 we have the Option to :

Enable HTML Extension:
Enabling this option will append ".html" to the end of urls

Okay what is the optimum setting on or off?
And why if it is better on or off?

Just trying to understand this new setting.
As we don't want to screw up our google listings.