I definitely like the look of the new numbers at first glance. With the revised numbers, SC's often became fairly trivial in my experience, even if you went with all hard DCs. These new numbers obviously give the DM more room to work with -- while also allowing him some coverage from the rules lawyers in the group.
I also think that the note about the all-in character is a good one. In other words, don't bother trying to design something that will be difficult for Mr. All-In because a) its not worth it and b) if a player decides to devote that many resources to one or two skills then they should almost always succeed. The key point to remember is that any character that is that specialized in one or two skills is almost certainly giving something up elsewhere, whether its in the magic item property/power department, a feat, power selection, or even an ability/NAD. There is that give and take, and since they gave, they should also get their take.