DW is viable, but not as easy as Xbow & quiver. The biggest issue is that chances are you loose 200 odd vita from not having a quiver.
Calamity & Danettas Spite is the most common route, but a decent rare with dex, crit damage & a socket is getting there. If I use my 10xx dps 2 soc manticore I gain about 25k dps, and a bundle load of vita from DML.
I run with just over 200k dps with a legacy nat set and run MP5 for keys with very few issues, but above this takes a long time. I run ubers on MP7 or 8, in a group, but DHs dont scale very well at higher MPs regardless of set up.
Personally I would only attempt higher MP with a DH as a 'challenge' as it is far far from efficient. I'd you want to run MP 10, use a barb.
Btw- off hand is just as important as the main hand, attacks vary from one to the next, and dps shown on the character screen is an average if the two.
Edited by Adeyj, 24 December 2012 - 09:19 PM.