A. Rawr has been pretty borked gem-wise for a few different classes for a while now. I don't know if Hunter is one of them. I do recall there apparently being a point where ArP was rated above Agi though. I could be wrong (I'm far from a Hunter expert--this is second-hand knowledge).
B. Did you need hit? If not, the Marrowstrike looks MUCH better to me. You can gem for Hit, if you need it, and grab the 4 Agility. Or you can go for Agility/ArP and ignore the bonus. Or go Orange, and get a little bit of all. The Orca spear has a blue gem--you're not going to be getting the (lolworthy) socket bonus with that.
Marowstrike:
106 Agi
Yellow Socket
--+4 Agi
57 Crit
154 AP
60 ArP
Orca:
112 Agi
Blue Socket
--+4 Agi
84 Hit
66 Crit
183 AP
You gain, like, 33 AP without talents and lose 9 crit. If you need hit, Orca is probably better. If you don't need it that badly, the ArP on Marrow is probably better.
Or, if you just need a little hit, put a
Glinting Ameterine in there for 14 Agi and 10 hit. You only lose 6 Agi from the socket over Orca.
I could totally be wrong, but Marrow just looks better to me. Remember that higher ilvls doesn't necessarily mean an upgrade.
Note: the ArP is 4.87%.
All in all, seems like a sidegrade at best. I can't imagine a noticeable DpS increase from either.