noob question about hemoFollow

Hello all,

apologies if this is a really noobish question and as this is my first ever post im sort of expecting to get shot down a bit over not knowing this....
when i started to level my rogue i read the forums to see what worked and what didnt etc as although i do solo quite a lot, i still want to be at a respectable level when in a group. I have always loved the Sub tree and although it isnt my main spec anymore i do still like to swap back into it for fun (my two specs were prepilate and combat but im in the process of going full assasination with HfB to see if that works better in guild raids).
anyway, onto the point. I read a long time ago that Hemo should not be used with daggers. I even seen a few threads with some people getting flamed for using them with it.
I have never really understood why?? although i have always gone along with it as some people like to do the math etc but i have never seen anything actually explaining it.
Due to this, at the moment I am using a mace MH and dagger OH, but i wanted to ask the question, is it still a big no go to use daggers with Hemo??

and on a side note, as i mentioned i am updating my talents. is prepilate still the main pvp spec? and what is the current best pve spec?

Thanks for the help and hopefully not flaming me :)

cheers, i thought it may be to do with the speed. i just knew not to use daggers but not the why...
prepilate is going as far as muti in assasination and up to preparation in sub. its a build i have seen in a few of the threads on here so i was using it for a while.