Yep, those conversions don't interest me in the slightest. Much the same as I'd take a GT3 over a Turbo any day of the week.
I think on some ways you're right:
The RS4 is superb in the slower stuff but its weight and trans loss hurt it elsewhere.
The M3 has such a good chassis, you lose the sensation of speed in it a bit.
The C63 is a bit on the edge of lunacy, so the noise and willingness to light its back end up add to the occasion.