The last three times I have played against Space Wolves with my guard, mind you I have my own Space Wolf army as well, they have been playing these 'net lists' with Razor Back spam and small Grey Hunter squads. While they have some success with their armies, its never with their troops that they are successful. Meaning, its always the Thunderwolves or Wolfguard that do the majority of the killing while the Grey Hunters are picked off one small pack at a time, never really accomplishing anything. Quite simply these smaller packs don't have the stamina to slug it out in a fire fight or close combat. They are just big enough to be annoying, but small enough to get swatted away, these are the mosquitoes of 40k.
Last time a ran up against 'razor spam' I ended with Grey Hunter squads plowing into my Guard blob one at a time and getting overwhelmed by the hits, they simply didn't have the staying power to hold up to the abuse. One by one they were ground to pieces as the blob more inexorably forward. Part of this was the players fault for feeding them to me one at a time, but part of it was my fault for stunning and immobilizing his rhino wall as it moved forward. The 'razor spam' relies too much on getting everyone up at the same time, and by focusing on one transport at a time with successive fire from units you have the opportunity to disrupt the timing and the spacing of the units. Once one or two rhino's get stunned or immobilized players aren't going to stop the advance, they simply press on into the attack with the guys now spread out over successive turns instead of hitting all together in a decisive knockout blow.
My typical Grey Hunter pack is one Wolf Guard with power fist and combi-melta, nine Grey Hunters with one melta, one power fist and one banner. That unit hits like a brick in close combat and has enough bolter fire to make any self respecting guard blob, or other horde type blob, think twice. Against vehicles it has the two melta shots and two power fists, if it comes to that, which should generally be able to fell all but the toughest of vehicles. Against troops the bolter fire becomes a torrent of casualties and then comes the assault, all of them are armed with two close combat weapons, where they will re-roll any zeros (pray I roll two's!) thanks to the banner and the two power fists tossed in for nasty critters. Really its the swiss army knife of troop choices.
Placing the pack in a rhino allows for 10 dudes and saves points over all those expensive Razorbacks running all over the place. The minimum most people put on their Razorbacks is the assault cannons or the lascannon twin linked plasma gun combo and those add up fast. In fact, by putting either the assault cannons or the lascannon twin linked plasma gun combo on a Razorback instead of a standard Rhino it is costing you the equivalent of 3 additional Grey Hunters. Are the assault cannon shots worth the loss of three more bodies in your troop choices that can suck up wounds and deal out bolter fire? I doubt it. Oh by the way we are still talking about the same armor value on both tanks, is it worth 3 Grey Hunters to put the gun on the same chassis that an autocannon equivalent will go through like Moses parting the Red Sea?
Weapon ranges. Given the typical tournament board now almost universally contains one piece of terrain that blocks line of sight, the short range of the plasma and assault cannons is more of a liability than a benefit. Once I get the immobilized result I want on your Razorback, with my longer ranged autocannons, I can avoid it all together; rendering it useless until I decided to take it out.
Kill points, more smaller units more kill points. Victory points, Razorbacks are worth double the victory points. It is precisely the same chassis, same damage table same everything, the only benefit is you now get to use up an additional 'weapon destroyed' result. But essentially I'm going to get double the victory points for the same shot. All while giving me more opportunities to rack up kill points with the smaller and easier to destroy squads.
I must be missing something, I just can't wrap my head around this idea of Razorback spam. But I know people use it, I know they swear by it, I just can't see where the huge benefit comes from.