Wow I couldn't disagree more.
Admittedly I believe it also depends on the mic to some extent. With an SM57, the pre can make a really large difference. I find it is easier to place and the tones stack a lot better and fit in the mix easier. It is a balance of cut, power and lack of harshness.
I do a shootout almost every time I mic up a new tone. I place it using an A12. Then I do blind tests with the band, volume matched. It is easy for me with the patchbay and a re-amped signal. Even they can hear the differences right away. They always pick the nicer pres. Sounds fuller and bigger and sits in the mix.
I will admit, that once, I had an industrial band pick an SM Pro Audio PR8 channel that I modded with OPA2134's. I keep it around since it does sound great on acoustic guitars and vocals.
Compartively... my DigimaxFS sounds veiled without any richness. Behringer, plastiky top end and upper mids. I try them every time just to be sure. It is subtle but it does make a pretty big difference.
I mean the vein is the same, the tone is mostly there. But it is these subtle differences that can drive you crazy in mixing requiring crazy EQing, compression, and saturation plugs and the like. Vs. just bringing up the faders and quick low-pass/high-pass for rumble and to fizz and maybe a slight cut here or there to make room for other instruments.
As always YMMV.
