I had a chance to ride a 15m back in fall and recently on my trip south I rode 4/6/8m Ghosts and I missed an opportunity to ride the 2.5m. We also had a 12m on the trip though I can't say I'm a fan of big kites anymore, and 12m is huge. I'd rather take a 10m on long lines and have more fun. Same trip I rode 5m Ozone Reo, which one person referred to me as "best wave kite ever made".
I'm bringing up Ozone Reo because Ghost is certainly same game, as I felt it and just as good if not better, so to compare it to "best wave kite ever made" - well, it's a good benchmark. Well met benchmark.
Ghosts are very light, material and detail quality is top notch. Large inflation Boston valve is now standard on all sizes so no need to use 9m nozzle for tiny ones. Stable kite, relaunches great and one strut makes difference in relaunch and being a structured wing.
8m and 6m sizes did great, I liked 4m even better but who wouldn't like a quick wing, the smaller ones get quicker naturally.
One thing I liked SST better for - I loop/downloop my kites a lot. I just enjoy flying a kite while going and in that regard both Reo and Ghosts delivered loop more powerful than I occasionally wanted. If looped from zenith or from edge of the wind window they swiftly pivot turn and don't deliver a power surge, just nice extra drift. Well, if you loop from 45 degree angle they generate more power and it could be used if you're going down the line but it could be also messing with your tack ripping you off the board.
But then again, not everyone loops the kites all the time and Ghost makes a great, lightweight companion for people who are less chaotic on water than I am
For folks who like their kite to turn on the spot - stay with SST