Soft synths run with out aliasing at 192khz, this vastly improves them for leads and shimery sounds. It also makes fx not alias and render with more resolution, if you use a good khz converter i am told that the benifits are huge for VST soft synths.
"I have done this test myself. http://dl.dropbox.com/u/15285948/44100Hz.wav http://dl.dropbox.com/u/15285948/96000Hz_r8b.wav http://dl.dropbox.com/u/15285948/192000Hz_r8b.wav
Same synth rendered at 3 different samplerates and converted to 44.1. The difference is clearly audible.
EDIT: Converted with the aforementioned R8Brain,it's great."
^ above in quotes is from a kvr site talking about the benefits, this is the proof, listen. the difference is amazing.
Running at high frequencies is not going to make recorded audio better really, but it will reduce aliasing, meaning if anything you record is above 20khz then it will cause aliasing, at higher rates it will not, you can filter it after the fact during conversion and have no aliasing.
The big problem is that all VAs alias past a3 on the keyboard, this is because it is making feqs above nyquist, even though you cannot hear them they get mixed back in as aliasing noise and raise the noise floor of the track, and add unmusical distortion. This is what leads to ear fatigue in digital audio. There is a truth to this and i have heard it myself, i could not stand cubase until i ran it at higher rates, then it opened up and sounded good.