Yes and No. While Ancient Tomb is wasteable, it's also 1) more land, 2) and the ultimate land, so you play it as the final land to fuel Hurkyls.
I'm not as sold as Matt E is about Leylineb of Sanctity being that vital to Dredge's continued success going forward, but I'm no longer a Dredge expert -- so you'd have to ask other folks about that.
I've gotten really contradictory feedback on the card thus far, however, Mark Hornung is an advocate of playing Void in the main (to win the mirror and turn off Will) and then siding in Sanctity. He went 5-2 in Champs (17th on breakers, lost rd 7) and split the finals of the Saturday night tournament.
I honestly have no really strong opinion of the card, I just think it *should* be good based on my previous experiences with Dredge and other decks. I have probably played less Magic the past 6 weeks than any other 6-week stretch since March 2007.