G'day again,
I know what you mean - hard to fathome there's really a problem when you've solved it in one instance
Let's say you've been called up to go to some little backroom studio, and there's some airborne electrical noise such as from a distribution transformer next-door, or the aforementioned light dimmers, or a squillion and one other reasons for electrical noise.... This will impart _some_ noise, even on your well sheilded guitar. As an example, I have a rewired Telecaster (single coil pickups) that has earthed copper foil lining every cavity - even the scratch plate. In my environment it's _acceptably_ noise free but certainly not noiseless. My guitars and basses with humbuckers are much quieter, but this telly sounds excellent so it's not getting changed!....
So... A track is recorded, and though it's relatively quiet, it's going to impart some noise into the finished track - particularly if it's used on (say) 2 backing tracks, and a harmonised, double tracked solo (suddenly there's 6 guitars on the recording.
Now - as a recording engineer, I'd be a dunce not to minimise the noise on each of those tracks so the quiet parts of the song are in fact quiet - This is where good noise reduction plugins are useful. Sure gates are used where the instrument is not playing, however gates arent suitable to remove noise in many situations. So.. the plugin takes a sample of that noise, then uses digital magic to remove it from the track.
They work well - particularly the expensive ones (I have a few).
So - If that was included as a block in the axe fx - I'm absolutely sure it would be useful for some. The price would of course be that each room, each guitar, and in some cases each session, the noise is different so the learning and applying of the filter would become part of the standard 'setup before playing' routine - along with tuning etc.
Once again - I agree that it would be nice to have noiseless gear all the time - but It's not always possible. This is particularly true when you are recording other peoples instrument (they dont want you messin with it!)
Anyway - that's just my take and I'm not the only guyu with an opinion.
Thanks
PAuly