Its true about the SL/SL it does give you one of the best advantages in pvp, but if it may help (have not tried arena nor this spec so forgive me if it blows) to do what my mate did, he specced FG + destro for some reason but the advantage is that you get 10% crit in your talents only and adding that to your crit makes you go pretty high with low gear stats.
About the Dread and Felweave, do not go dreadweave at all, you will have much more use for the cirt on the felweave though you may not think so, extra stam can always be socketed or enchanted but, crit may be harder or more expensive. I went for the dreadweave thinking just like you, that if felweave produces crit then i will go dred as i dont need crit as DoT'er. I regret that extremly though im aflliction, because you WILL be casting shadowbolts and it IS nice with that crit, and if you specced the first five points in destro its even nicer increasing the shadowdmg taken by your victim with 20% four times.
As the other dude said, scryer is the way to go
post got a little long here hope that at least some of it have helped
