I did experience unexpected volume difference switching between Ideal and Authentic on the Sat switch, on a different model than Herbie ... That was the only oddity I noticed while trying to create presets, but I think I only did it once. It was more extreme than I would have expected. Is Ideal really supposed to be, like, twice as loud?
I'm not sure about the amount of the volume change, but this is by design. From what I recall, 'Ideal' mode was added after the saturation switch was improved to be more realistic. The change came with a volume reduction as the real world mod would have - this became the 'authentic' mode. Ideal was added as an alternative that didn't have the volume reduction (and maybe other things, who knows).