Holy Rosary is a true classic, easily one of the best Mystic cards in the Core Set and still a top performer many years later. So when Crystal Pendulum came out, I was initially a bit resistant to switching over to this. Sure, for Jacqueline Fine with her built-in token manipulation and 9 Sanity, the Pendulum seemed like a slam dunk. But elsewhere, was it really worth giving up the concrete benefit of 2 Sanity soak for unreliable card draw? Most of my Mystics don't run a lot of token manipulation at lower XP levels. And this is the same class that must start every single campaign with 2 mental trauma (it's in the rulebook.)
But the more I weigh the Rosary and the Pendulum, the more I've found myself swinging in the latter direction, if you know what I mean. Practically speaking, even without any support, the Pendulum represents something in the neighborhood of 25-30% of a card every round. And the thing is... that's good! That does add up over time. I think it's at the least highly competitive with 2 Sanity. And that's just the floor for the Pendulum. Factor in the random token manipulation effects you may have wanted to run anyway (Diana likes her Dark Prophecies, for instance), and the Pendulum does better.
Moreover, the Pendulum tends to scale really well into the late campaign. Most Mystics want to pick up the really powerful token manipulation effects like Grotesque Statue and Seal of the Elder Sign because, well, those are great cards. And they certainly lead to more draws from the Pendulum. And in the mid-to-late campaign, you'll miss the 2 Sanity from the Rosary a lot less, because you'll have options like Deny Existence V, soak-heavy Charisma builds, etc.
So I think it's very close between the Rosary and Pendulum in the early campaign, and then as the campaign progresses, the Pendulum tends to get better and better. So I've found myself tilting that way recently, and I've been happy with the results.
A final note. The Pendulum is a fiddly card and does have the potential to seriously slow down the game in multiplayer. If you're going to run this, I recommend memorizing the contents of the chaos bag (which is helpful for good gameplay in any case), so you can be quick in making your predictions. Be mindful of your pace of play here. No amount of extra draw is worth dragging the game to a halt!