Yep, it's a bitch. I'm going to look into it, there should be a way of managing this. I wanted to do some insetting recently and the lack of a proper method was really annoying :(
I think the above image shows why extrude/offset isn't a good substitute for an inset function. Offset handles convext angles perfectly but fails when it comes to concave ones.
there is a solidify script... think if you are using this on a face would do somthing like inset... http://www.creativecrash.com/maya/downloads/scripts-plugins/modeling/poly-tools/c/p3d-solidify
Mayas bevel is sort of strange, it takes the selected faces and applies the bevel to all the connected edges instead. All someone needs to do to write an inset tool is post offset run through all the new edges leading inward, determin their length, and lengthen/shorten them based on the difference from the offset value…