I have been running a Scarred Lands campaign since the setting first came out, and so I'll share my experiences with converting other material.
Firstly, here is a list of published adventures I have managed to use or intend to use
-The Serpent Amphora trilogy (heavily modified)
-DCC14 Dungeon Interludes (Adventure #2, only backstory and level CR adjusted, and plan on using adventure 5, the tower in the tar)
-WW16000 Nature's Fury (The Crystal Tower, modified backstory and CR, added another level and some setting specific NPCs/monsters)
-The Gates of Firestorm Peak (with some setting specific critters and a lot of reworking)
-Sons of Gruumsh (used the "Tougher Sons" free web download, added the macgauffin and otherwise beefed up the CR of the foes, and changed the backstory (no rescue))
-The Tower of Deception (free Monte Cook download adventure, changing to 3.5 ed and only changing spell lists and treasure found)
I had considered using several more of the DCC line, and might yet still. I have used several maps from Dungeon magazine and stocked them with my own statted NPCs. While the nature of the Slarecians, the Slitheren, the Titans and their druid and sorcerer followers make the setting unique, it's still a D&D setting. Urban adventures work fine if you just insert the propper backstory and ground it in the setting. Wilderness setting adventures work fine if you just swap out some stock D&D critters with SL ones. There don't seem to be a whole lot of true "dungeons" in the base world, but you can just drop them in (usually with a long and dangerous wilderness trek leading off). Huge parts of the world are only scantly mapped, so dropping things in are not that hard.
It's easier to point out the areas where it's hard to insert "standard" trappings than it is to rule things out. For example, the "hoards of evil undead" are harder to do, because there is no "hoards of evil undead" deities. Sorcerers are profoundly different from wizards. Most of the "true" dragons all live on a faraway continent (but make for a truely kick-arse faux oriental backdrop). Many of your "evil" priests will actually be druids, and the real evil priests will help you fight them! Demons and Devils aren't the foe they are in standard D&D either, and psionics, while present, are a different kettle of fish altogether! But on the other hand djinn and the elemental lords are wide open for fun.