Three questions:
1) Can you cap fullauto and burst on the OFAB Shark Mk6?
2) Do you mind losing the snare proc from the Dshark?
3) Do you have a load of add proj damage imps/symbs?
If 1 = yes, and 2 = yes, and 3 = yes, then use OFAB Shark in pvm.
If you don't cap FA/burst, or want the snareproc, or don't have proj damage in symbs/imps, stick with dshark in pvm.
For pvp stick with Dshark as well. Because of the +20 AAO.

Lupusceleri L220/24 Agent.
Silversmith upcoming TL5 twink.
Wolfseye L110/12 Adventurer (towertwink).
Lysdexic L90/9 Agent (Mimic Enf towertwink).
Aesculapias L21/2 Doctor (ancient).
Aaaand various other alts.