Even with 50% taskers, hitting the 4.15 breakpoint is extremely difficult. Currently impossible with the gear I have now. You need attack speed on EVERYTHING, so you're going to be sacrificing some dmg.
1H xbows don't hit as hard as bows, so unless you're at a higher breakpoint, 1H xbox are simply worse. The 20% dmg boost is probably enough to make up for that difference, but then Etrayu has up to 20% cold dmg. Not to mention I'd lose even more dmg on the Calamity by rolling off DMG for IAS.
Sentry attacks don't proc MFD either, so you have to do it yourself. Trying to multishot everything would drain hatred so damn fast.
As is, I wouldnt even use the Calamity over my Windforce.