wof against necros is overrated because good necros who are fast enough at WSGing and spotting traps will get out of your traps before they do much damage. LS is better here for the projectile moves faster (fast enough) even if you can avoid (some, but not all of) the straight shots by running in a curve/zig zag.
wof is nice for the initial stun but bad at dealing real (trap-)damage unless you have a good net of traps lying as the initial stun kicks in, which wont happen too often against a good opponent. throwing wofs per namelock and keep chainlocking wont help a lot because the fire wave moves too slowly.
generally sins with maxed mindblast tend to have a much easier time catching necs in the first place which means that almost all hybrid variants are worse against necs since they are just worse at chasing in general.
unless you play something uncommon like a max mb ww/wof hybrid
on trappers, fireblast is also nice to have sometimes but becomes less important the better the nec player is since you can anticipate it by wsging early enough and counter possible stromping situations by preventive running/wsging. your best bet against top necs is usually chainlocked ls/mb sequences with FB usage whenever he tries to tank (depends though, sometimes spearwalking/sidestepping is better).
generally, trappers can and should play 102fc cc against necros which, for me, feels much more comfortable compared to 65fc.
i personally like trappers better than ghosts against necs but i know that many good sin players think the other way round. i dont know for sure though since i havent tested a 102fc ghost setup against necro, but i think that 65fcr is just not enough against a good nec most of the time even if you lose highlords and other stuff in order to get it. also, maxblock makes it a lot harder for ghosts so i duno. i personally prefer trappers. it just feels most well-rounded for me against necros. you have more tactical options than ghosts are it's overall more forgiving if you make a mistake.
but i think overall, good ghost and good trapper are a tough fight for any necro.
i liked austin's trap vs necro videos because they demonstrate effective and versatile dueling style:
http://www.youtube.com/watch?v=161j0uQPfvo&feature=channel_pagefor ghost vids .. dont know there are not many around. but i think ziecheik and tienje have some unline, just PM them. they sometimes dont answer so dont hesitate to pm them 2 or 3 times. they dont mean it like that, they just dont notice it