Honestly, with the disadvantage brought on by the Mindless S.A. I honestly believe a LUck Stone is a great investment for the Necropolis.
As much as Mindless has disadvantages in no focus, and no support, it does have serious advantages as well, Shaken comes into play alot in the game, and combined with undead, skellies and zombies are immune 2 pretty important game states (the other being poison). Considering just how cheap they are you can easily make up for a lack of focus and support with shear numbers in my experience. Not worrying about Fearsome, Naueseating, and Shock is very cool (especially Fearsome).
More on Railor:
One of the great things about Railor as a sergeant is that he can field 10 soldiers (plus an Elite), which is more than the 6-8 that most can bring (and he can field all Necropolis soldiers except Crimson Knights). He can cast Necromantic Surge and Life Drain, making him the one of the only non-unique healing capable models in the game (so he is great support for Solos, Leaders, and Elites in your army). In addition, if you drop 3-4 Railors on the board, it gives you alot of chances to counter Burrowing and Flying models with Winglock and Exhume.
Honestly he is the undead leader I use the most, I have 4 of them and usually put at least 2 on the table, so I must like them Hopefully I've sold him as a worthwhile investment (Heck, at 40 points you can't really go wrong).
I haven't used these guys before, mainly because I dislike the sculpts, but I've always considered them more of mop-up units, killing models on their last track and dashing away. But a handful of them with swift attack could do some serious damage to full track models, I might have to revisit them as being part of my necros.