my entire playstyle as sub revolves around killing -> restealthing on cooldown, meaning that having a higher chance of crit ambush outweights any benefits of haste when engagements are confined to just a few seconds repeatedly. For sustained group fights, especially as combat spec - and some assass from what I've seen - haste may benefit you more, yet even then I would run crit since there's no need to ever be mid fighting as a rogue - you have boomkins and monks to fill that role, while you should be on efc and running between zerk huts 100% of game in wsg. I think sub's role is currently at it's greatest in cleaning up during ongoing team fights - ambushing to immediately kill any targets then restealth and repeat as needed - which can be best seen in av / eots. I often ran haste head for av and vultros for wsg but that's pretty much the only changes I ever needed to make, despite having enchants on all potentially useful gear pieces.
these were my last 10 games before being banned - I am yet to see any equally effective rogue playstyles for non-wsg vet - haste stacked combat is definitely viable as well, yet if played incorrectly the majority of your dps will be off of bladeflurry padding instead of applying actual pressure.
as I mentioned in my earlier post, it's 20-29 - with gear and common sense any setup can and will succeed. this is my preferred method of playing but I can see why many people would rather stick to just combat when rogue is a total joke at the moment - despite its burst power, the class has little utility compared to cata and is far less powerful than it was in MoP, leaving combat as the popular option for current facerolling (and hey, who doesn't like pressing 3 buttons to global people? That's this bracket in summary.)
a viable setup? sure, but once again it's all opinion based - if two setups can perform the same at equal effectiveness, in the form of global'ing (preferably via 1 shot) the efc, then it's pointless to declare one as any more effective than the other. a brain + common sense is all you need to do well in this bracket - and if we're going off of the truly "best" 29 builds, your character clearly lacks the items needed to classify as bis - skullbreaker and gf'd enchants will lead to a significant burst increase if that's what your build relies on.
have fun remaining closeminded! I've seen hundreds of similar players over the years - hopefully a decent assassin / sub will show up to change your mind at some point.
to get back to the point of this topic - OP needs to try out all three specs and decide on which he prefers to play, as all are viable and will perform at the same level if played correctly.
