The GS is more roomy. Not sure I'd call the SS a tight squeeze though. The ski pole is nice on the GS, as is the rear deck area. Both extremely nice hulls. The SS is a little easier to drive IMO. If I had a GS for sale I'd say the same thing. The GS is a bigger boat and just takes more to keep it minding its manners. Both are well laid out, with lots of features. Yours looks very nice Whipper.
Slightly larger interior space and the rear padded deck as mentioned above are the strengths of the GS. Some things will be better inherently on the SS mainly because of its weight, size and more modern bottom design than the GS. The average GS is around 150to 200lbs heavier than the Excel.
Holeshot is better with the SS. Handling is easier with the SS. They both take rough water quite well. Top speed is around 8 to 10mph different with the same power. We've gotten low 90's with a well set up 225 ProMax on the GS. A well set up 260hp will put it right under 100. These were reasonable setups, with usable propping, normal load etc. In other words, we didn't cut every bolt in half and pull out every ounce of weight & run naked down the lake or run some 34P paperthin prop that was unusable for anything but topend. Mark Smiley from DesMoines Iowa ran a 150SS ProMax on his full weight SS Excel when he first bought it and run just over 99mph to see if he could get 100 out of it. So, they will run 100 with a 225 ProMax pretty easily. 110 with a 280, etc.
Horses for courses......Both exceptionally nice hulls. I prefer the SS over the GS (or its basser version, the XB2003), but I like the smaller quicker hulls better yet, like the XR2002 and XR2001, neither of which can take rough water like the GS or SS. Both the XR's have much less room. Comes down to what you are using the boat for, the way the boat looks, what compromises you can live with, price, etc. My XR2001 has a great holeshot, but it sucks at fishing, carrying passengers or pulling skiers.....Of course there was that time I got desperate and fished smallmouths out of her....LOL