the s-glass is cool stuff,,I made a bunch of test panels comparing 4oz s-glass to 4oz e-glass. 4oz s-glass isn't a replacement for 6oz e-glass,,not as rigid,,but in an A/B test with 4oz e-glass the s-glass stayed together kind of like the kevlar does. Impacts and punctures made the damaged whitened s-glass travel 1/2 the distance over the wood than the e-glass. On two kayaks that had only 4oz s-glass on the bottom panels there were still dings into the wood from rocks but there were fewer whitened fractures in the glass compared to what I've seen with e-glass. It's almost like the s-glass has some stretch to it in that the one layer of 4oz glass couldn't prevent a ding into the wood from happening but at the same time the glass threads were a lot less likely to break in the resin matrix.
two test panels really drove home the difference,,6"x6" panel of 4mm okoume with 4oz e-glass on both sided,,another panel with 4oz s-glass. Putting the e-glass panel on a step I pressed down with my foot until the panel broke. Did the same with the s-glass panel and the panel bent nearly into a 1/3circle without gross fracturing of the glass or wood, a LOT of whitened threads on both sides but no distinct fracturing along wood grain. With the e-glass the panel snapped with a clear fracture line along wood grain and shards of ply sticking through. On the s-glass one the panel was obviously damaged with whitened threads on both side but there was no through glass fracture of the plys.
I haven't done a test panel with the 3.25tightweave e-glass from RAKA but I suspect it's better than regular weave e-glass.