My quick summary on swat/S1, currently own '11, '12 SWATs and '12 S1.
'11 SWATS - good starting point but when they get near their upper wind range they get a bit wild, quite a 'forward pull', draft moves around a fair bit. Light and super cheap though.
'12 SWATs - massive improvement, way way more stable in the upper wind ranges and still the same grunty bottom end, still epic cheap
'12 S1 - Full baller spec, super light, super stable, look pimp. Not as grunty as the SWATs I don't reckon but they make up for it in stability and feel I reckon, priced as you'd expect for their premium sail but still way more competitive than a lot of other brands. Not as much as difference to the SWATs as pre '12 though.
Personally I've got some '13 S1's on order to replace my 5.2 and 4.7 '11 SWATs and i'll be keeping the '12 4.2 SWAT and '12 5.9 S1 as they are still sweet as. can't wait for them to arrive

Note: have never sailed a blade, so can't compare, marketed as a bit more grunty, bit heavier, bit tougher?