Shaft > Twitch imo. Assuming you have lvl 20 fanaticism, your IAS breakpoints with a Cleaver are 19/32/65/86. Butcher's gets you 30 and you can pretty easily get 20 from gloves, so Shaft + IAS gloves = 32 IAS bp, and Twitch + IAS gloves = 65 IAS bp. The life on Shaft and the stats on Twitch are a wash. The block chance on Twitch translates to approximately 20 or so less dex needed for the same level of block so let's assume you turn those stat points into vita:
Shaft = 4.31 attacks per second, 30% DR, +450 or so armor and additional armor vs. missiles which will be multiplied even higher by HS
Twitch = 4.46 attacks per second, 60 life, 20% FHR
The 30% DR and additional armor are way more valuable than 60 more life--30% DR alone will translate to triple digit mitigated damage in any serious fight. The drop in attack speed will hurt a little bit but not enough to justify Twitch when you're playing hardcore.