[Lars Dangly]

Borderlands, either the original or the recent reprint, is perfectly suitable for RQ III. The only minor issues might be encumbrance (the rules differ significantly between RQ II and III on this point, and the reprint at least provides no Enc stats for npcs) and the validity of some RQ II shamans and runelord priests (I'm not sure you can get away with all the same things in RQ III). Who can say about Mongoose. It really depends on whether they stick with the attributes and their ranges, percentile system, skills, armor, etc. If a basic NPC stat block changes dramatically there will be compatability problems because pre-generated NPCs are so important to running runequest.