Coloring the icons would be great for indicators, for example when the grid has a filter coloring the funnel icon would be great instead of coloring the background

We would love font icons as well instead of a sprite.  We would most appreciate the ability to use our existing icon font (to prevent having multiple fonts on a page).  This could be enabled through some icon class name mapping from Kendo's icon names to ours. 

Browser support is very good:

http://caniuse.com/fontface

Sprites can also be broken when a page uses

<meta name="viewport" content="width / device-width / user-scalable, etc> (very useful for responsive apps).

Icon fonts are more reliable. The alignment and scaling of sprites can look ordinary unless you use the perfect font size/padding, etc - whilst font icons just work!

Already implemented for Mobile...how hard can this be!?

This is becoming a must. It is a GIANT pain to change the styling of the icons. Especially since there is no way to do it aside from writing custom CSS and creating new sprites. Which has ALWAYS broken when we update to the newest version of Kendo. 

There is no reason why this can't be done. It would also make it easier on your dev team, because it would require much less CSS and would give us the ability to easily style or change icons as needed using another set of icons if we choose to do that.