Huh? Check your revisionist history book.
First, that doesn't fit the description of a product or model upgrade in the least, and second, even if it would, the switch to Intel was not because the Intel chips were significantly better (they weren't; PPC at that moment in time had full parity with Intel), it was done to create a better future path. Intel had one; PPC was tapped out. But at the time they were otherwise equal.
And casual customers still don't even know there was ever a switch. The 2006 PPC Mac Mini is really just about exactly the same as the 2006 single-core duo Mac Mini that followed it, for example. If better, only incrementally so. The value of having Intel only became a reality when PPC became obsolete and would not accept Snow Leopard, which happened some 4 years later or more.
So none of this fits the description of an "upgrade twice as good as what came before", not even a little bit.