RE: Giant Aeromaster
I never built one with both swept. I suspect it might be a bit more severe or touchy on stalls, since you have in effect a smaller MAC than with just the upper swept. I've built them all with the upper wing swept, and either shorter than or same wingspan as the upper for the lower wings. The only thing I noticed different with the fullspan lower wings was a bit more 'float' on landing. The roll rate was about the same for both.