I only now read this thread for the first time, and did notice an inaccuracy on where to find the high affix level charms. Baal and Diablo are mentioned, but Nihlatak is not, whereas his monster level in hell is 95, so he can drop charms that you can then cube to find those incredibly rare affixes, for example the hibernal small charm.
I must add that I'd advise against running him in hardcore, due to the bugged vipers and his corpse explosion. Nonetheless, with the right character it's certainly doable, although aborting when encountering vipers might be a good idea. In this case, you would, for once, collect the halls of pain waypoint, so don't use a character you plan to run Pindle with, and teleport down (being a sorc or using teleport charges). You might want to use something to prevent his corpse explosion from working, such as for example Nature's Peace, just keep in mind that that only works for monsters killed by you (not by your merc, I'm unsure how other minions count). Shattering corpses (freezing monsters) or using corpse explosion yourself, or vines/dire wolves that eat corpses will work as well. I don't know how he compares to Diablo and Baal for his chance to drop charms, but he's certainly faster to run. Looking at the treasureclasses in TreasureClassEx.txt, I think Nihlatak is a better source of charms, per pick his chance of act5 (H) good is 3/(42+nodrop), whereas Baal and Diablo both have 3/(65+nodrop). Nodrop is of course determined by the number of players and is slightly higher for Nihlatak than for the brothers. Still, at players1, it comes down to 3/61 versus 3/80 per pick. Now does Nihlatak only have 5 picks, whereas Baal and Diablo both get 7 (but a maximum of 6 drops), which can even it out more or less, it's too early in the morning to do the calculations. A shame that the drop calculator makes Atma crash under linux, I really need to make my own. At higher players settings, the balance will shift towards Nihlatak though. In addition, since charms always spawn magical, you can ignore magic find (unless you're looking for Gheed's). Of course you can run Nihlatak far faster than Diablo and Baal, since you don't need to deal with the seal bosses and the waves. Just keep in mind that he has high poison and cold resistance and is thus likely too spawn immune. On the other hand, with no damage resistance, characters providing physical damage rock against him.
So the conclusion is this: if you're looking for charms, go visit hell Nihlatak.
Edit: all my information concerns 1.11. I don't know if there are many changes, but I do know of one from 1.10, Nihlatak does now drop a key every so often, lowering his chances to drop charms slightly. If that's the only change, then in 1.10 it would be 3/(41+nodrop) in the above. And a reminder, I only checked the chance to drop from act 5 (H) good, not his chance to drop charms, which are contained in this wrapper TC containing also gems, runes (upto zod), and other jewelry in the form of jewels, rings, and amulets.