There is no real benefit from what I have seen. I've tried it at both 99 (94 real with +5 from a Tally) and at GM (with +6 from a ring, or +5 from tally and +1 from ring), and have found that there is almost no noticeable difference between the two. That one extra skill point isn't really a game breaker, but being able to put it somewhere else is nice. If you have everything where you want it and still have a free point, might as well put yourself at GM necro just for the heck of it, heh.
Edit addition: I admit that I haven't really "tested" it a lot from a purely statistical standpoint, so, my observations are based completely from an "as I happened to pay attention while playing" perspective.
For the most part, the different forms are about the only useful bit of necro if you don't have Spirit Speak, everything else is pretty much rubbish. Even Wraith Form is mostly gimped without Spirit Speak (I think... you get little to no mana drain without Spirit Speak, right?).