A lot of times I disagree with you, but I agree comletely with this- why change coaches if you aren't sure its an upgrade?
I'll add to that too- everybody is always looking for the hot coordinator, but there is a big problem with that. It takes a completely different skill set to be a coordinator than it takes to be a head coach. Coordinators deal mainly in X's and O's. Head coaches are less analytical, dealing with people and some game situations. One of their major roles is planning out practice- sometimes down to the minute.
At this point, I am not for a change- if we had to change coaches, I would not be for Spagnuolo or Lebeau (who would never come back after his first stint here). I would be for UCLA coach Rick Neuheisel.