Re: swamp ash vs alder?
I have G&L Legacys with both swamp ash and alder. Same neck woods, same pickups.
I find the ash tone is less dynamic, more focused, rounder, sustaining. The alder is more open, airy and with more dynamic range.
For the most part, I have no preference, except for one song that my band does that I prefer using an alder guitar for a more acoustic guitar-like tone. As for the rest of the material, they are interchangeable.
Bill