hi gents. i've done a fair amount of searching and reading up on these guys, but bare with me... i'm in the market for a new head. looking for portability, power, tone, and reliability. these two are pretty much the main contenders. i gig regularly, and have been (happily) using a gk400rbiv for quite a few years with no backup. After some recent issues with our PA heads, i'm thinking having an extra amp would be a good move. i've been waiting for class D to become more reliable and consistent, and these two seem relatively solid. 500 watts is more than i use now, but the extra headroom would be nice. i'm using a 2x12 dr. bass cab (got it in '05 - works great, sounds good, controversy aside...) at 4 ohms, and it's always plenty for the venues i play. my main bass is a Stingray 5, and it goes straight to the amp. no fx. very happy with the GK tone. always get compliments on the bass sound. i'm thinking about either sticking with the GK family and saving some cash, or jumping it up to the Aguilar for a change of pace. the new head will probably become the main gigging head and the 400rb will get backup status. i'm not into crazy treble, and don't do a ton of slap work. i'm usually go for a more punchy tone with a lot of note definition, and i like growly mids and a little touch sensitive drive. any thoughts on these two heads? would it be worth the cash to grab the aggy? i'm thinking it would be cool to have a different flavor, and from what i've seen it can get some cool driven tones, as well, which i like. a little edge is good! thanks for reading - any input is appreciated! cheers.