My bet is that it's the 1/4 turn throttle. It requires a lot of wrist movement to get it to full open (or close to that point) and to hold it there requires an unnatural wrist position. When I do my more spirited rides I notice my wrist getting tired simply from keeping the throttle open so much for so long. Try regripping so that your wrist is at a better angle when you're at full throttle. Or you can try to do a 1/5 throttle conversion.

how do I change throttles out?  Never even looked into it but I think it's what i need to do..

Pablo has http://pantablo500.tripod.com/id33.html that on his website. The stock SV650 is a 1/4 turn as well, so that won't work alone. Yours is a single cable throttle though, isn't it? It might be a bit harder for you then, as not many bikes use single cable throttle now days.

....I run an 03 R6 throttle tube on my SV cause it's 1/5th turn..the only thing needed was to file down a little bit where the cables hook in....10 secs on the dremel and she was ready to go....it is a lot cheaper and more user-friendly then the BRG method....I don't know if it'll work on a GS....but it might just be cheap enough for someone here to attempt...

Since everything else has been suggested, the only other thing I can think of would be the positioning of the controls.  I suggest rotating the brake lever assembly down/mirror forward.  Also, try just palming the grips, not curling any fingers around them, except the thumb.  Keep all four fingers covering the levers (and this will really show you if you need to rotate the controls down; you can do this just sitting on the bike, if it feels like the levers are not allowing your fingers to curl naturally over them, and your wrists feel like you're doing push-ups, you need to rotate the levers down).  Just palming the grips while riding also helps learn counter-steering.

is there any aftermarket throttles I can buy?  i don't mind spending the money if it's going to be more comfortable..  I guess I'll just look myself actually.

I hae the Throttle Rocker. It works great for me but maybe not for everyone. I have a 30 minute commute on the freeway with a constant speed of 75. TR makes it very comfortable. For in town riding, not so good. The TR takes some getting used to. Now that I am used to it, I wouldn't ride without it.