How do I get the Start button centered when start11 is managing the taskbar?

You cannot.

The enhanced taskbar features are not compatible with centred start button.

You can centre the taskbar buttons from the more taskbar settings button in the taskbar page however.

If you do not want the ungrouping and multiple lines and drag and drop support you can disable let start11 enhance the taskbar and you will be able to centre your start button.

The "enance the taskbar" makes the icons look SO much better than the default.  That's the only reason I use it.

Will this ever become a feature, or just something you don't plan on supporting?

Thanks.

+1 that I would love this feature

To give more detail: Whenever I move my mouse to bottom left to press start, I often move it to the other monitor accidentally and to move it back takes an extra second.

Oh I see now. The feature is supported but only with a Maximum of two monitors. And I have three monitors. Oh Well. 

1 more update. I downloaded the beta version of Stardock and it supports the setting even with 3 monitors. Great job Stardock, thanks!