Count me in as a convert too! I used to be a bigtime Ezzy fanboy, still am, but due to a few factors such as weight, wanting to do more freestyle, cost and super positive feedback from those who own them I bought a 5.2 SWAT to try.
The first thing I noticed was the weight, it is MEGA light, as swoosh mentioned the S1 is about 100g or so lighter but the SWAT is still an incredibly light sail. The low end grunt seems really good, better than my Ezzy's i'd say but it definitely suffers in the top end stakes; then again I don't think you'll find a non cammed sail that is more stable than an Ezzy panther, they are insanely stable. They also run a large boom cutout hence have a very short boom (5.2 swat runs a shorter boom length than my 4.7 ezzy) and also have a straight cut foot which is great for FS and waves as you hardly ever chafe your shins on it.
Basically if you are after a light, cheap, strong, grunty, super flickable wave/freestyle sail I don't think there is much else on the market at the moment that can compete on price/performance, I have since ordered a 4.7 and a 5.7

Note: I rig mine on an Ezzy 400 (similar to powerex), it seems to rig ok, would be interested to see it rigged on a Severne mast to note the differences, it might improve the top end somewhat as it looks like it wants a slightly stiffer top mast, someone else might be able to add some light to this?
Pros:
-weight
-cost
-short boom
-straight cut foot
-low end grunt
-100% xply
Cons:
-top end a bit sketchy
-fairly bland if you're into bling but they are that price for a reason and I applaud Severne for it...legends!