Toni,
Guild's dual truss rod system is unique in the 12 string world and distinguishes Guild from other crafters. Dual truss rods were incorporated in all Guild 12 string models until the move to NH. IMO, the dual truss rods signify Guild's early identity as the standard in 12 string guitars. I've owned many, many 12 string guitars; five respected brands (Guild, Martin, Taylor, Breedlove, Epiphone). The only ones I've kept are Westerly Guilds with dual truss rods. They stand the test of time...
Many years ago, I absolutely ruined one (not a Guild) by tuning it to concert (440) pitch and neglecting it for almost two years. It is now a fine wall hanger art piece.
I keep my Guild 12ers tuned down a full step (to 'D') and capo up two frets to achieve concert. Putting a capo on the second fret is an easy thing to do. Dual truss rods; stepped down to D. Sleep well at night...