+1
Radically different is right. There's definitely something wrong with the IIC++ model. I wouldn't say upper mids though, more like low mids/"mid" mids. When you select Latest, the amp model gets a lot darker and really raunchy sounding. It also gets a lot louder.
Oh well, guess I'll roll back to 4.01 beta until Cliff (hopefully) posts a bug fix.
Yes, there's some wrong parameter values in that model associated with the new modeing. You don't need to roll back, just set the Modeling Version to 4.xx.