CPU speed alone doesn't indicate overall system performance, nor do synthetic benchmarks. The PPC mini had a discrete GPU with dedicated RAM, and OS X at that time was mature on the platform and very performant. The first Intel mini was a Core Solo machine that was horribly underpowered, had Intel GMA 950 graphics not even powerful enough to properly render QE/CI without stuttering, and was hobbled by a very slow system bus. Intel Macs didn't start performing better than their PPC counterparts until Lion was released and the second generation of Core 2 CPUs with faster system bus and higher clock speeds came about.

I get the point you're trying to make, but unless you owned both the last PPC mini and the first Intel mini at the same time, as I did in 2006 (and still do), you have no idea what you're talking about.