Well, considering at 500 points id be running a CCS with 4 Melta in a Chimera, plus 2 units of MeltaVets in Chimeras, i dont think a Land Raider would be too much of a problem.
Then you run into the whole matter of getting those melta's in range, and when they are in range being able to shoot, and this and that and so on. (Don't get me wrong, three units housed in armour 12 fronts toting three or four melta's will probably get in range to at least shoot, if not do the job, its simply a matter of how many get there.)
Personally, I do not have any love for smaller lists that seem to rely on the land raider to win the game. It becomes such a point sink, and if your opponent can remove it then your generally fucked. Honestly, take the raider out of this list and thats 50% of the points in one go, its no easy task but that is a huge chunk.
I encountered this many times in my games with my shadow-company between the 750 and 1500 point ranges. (One of the first was 750 chaos, that land raider went down the turn my tactical squad dropped in.)