Have you guys (since you're working on the new mat. editor) watched these videos? Because truly, VUE's mat editor is the coolest mat editor and I love it. Of course, since KT's instancing brush, I don't use Vue any more...
One important feature of Vue's mat editor you should consider:
you can save settings in a little mat editor settings file with a little save button. So, for instance I can create a color ramp to modify, based on the objects Z coordinates, from the bottom of a hill to the top of the hill,
you can go to LOAD>and pick from several premade ramps of color sets or just many preset solids, or whatever. But you can also make AND SAVE FOR FUTURE RE-USE your own procedural ramp colors (FAll colors, sky colors, rock colors, mud colors, etc.) I used this feature to make some work trucks all muddy near the ground, but cleaner towards the tops of the vehicles.
Of course, I doubt you are going to get into the complex node editor like Vue's... but it's incredibly deep procedural shader choices and options are really something you should at least see. You can see them in the videos above.
I am still hoping for something even Vue does not have... a procedural customizable grid... what a powerful procedural that would be for making bricks, tiles, sidewalk cracks, masonry of all kinds...
Here you can catch a glimpse of the number of diff. procedural mats they have.
http://www.art-head-start.com/vid/Vue_Mats_2c.html