I'm coming from a pair of SST 6 that are about 7 years old, and I just got a new pair of Tour Ultras, and love how they fit, but there is a point I do have to make... 

 

When I was starting with them, I put in the 6 sole, and took a couple of shots. What I found, I hope I can find an answer for.

 

The actual leather that surrounds the sole you put in (That's the best way I can describe it) is very slippery, and caused my foot to slip a little as I walked. I could see that being problematic if I was using something like a 4 and the sole surrounding it is like a 10. 

The sky is falling

The end is near

The final warning

The sun disappears. 

 

My arsenal

 

http://www.flickr.com/photos/67160612@N08/ 

Assuming you have a wire brush, brush just that area, lightly, to roughen it up. It will make it more like the #6.

 

I have the opposite problem, I use the insert sole.The sole material surrounds the inserts and it is stickier than the inserts I use. I  have to allow some dirt and dust from the floor to accumulate to make it closer to the insert's level of friction.