Over in Castle Whiterock, the PCs hit into a fairly dangerous trap.
It's a good illustration of something I noticed in using D&D-style adventure approaches to GURPS - traps, unattended and unminded by active, intelligent, and hostile forces, are not as lethal as in D&D.
One thing about D&D that GURPS doesn't have is the attritional aspect of most resouces. In D&D, especially AD&D as I've played it, resources bleed away from a finite pool. You only have so many HP, so many spells, so much healing. Extra time doesn't help much - you can lose more HP in a 20' pit than you can heal back by rest in a week.
Because of this, traps left unminded generally just cost replaceable resources - you lose HP, but that can be healed with magic that costs FP that come back in minutes. Repeated healing penalties mean this spigot isn't endless, but it's not nearly as limited as in D&D.
For a trap to have a solid, lasting impact in GURPS, it needs to be lethal, crippling, destructive (to equipment or resources), or all three - and a good way to make it so is to connect it with active threats.
A reverse gravity trap with a force wall is nice, but if there are foes who can take advantage (perhaps fighting on the ceiling, and you can only reach them by "falling" up to them), or who have effective ranged weapons unimpeded by magic, or area effect attacks - then it's a real threat. A pit is good, but a pit that drops a few PCs in and covers them up as foes swarm in to attack the rest - that's a winner.
Such traps have a real threat, not just a sigh, puzzling out of the most efficient way to solve them, and then a solution followed by a short rest - perhaps even no rest if your spellcasters rely mostly on Energy Reserve.
For GMs prepping old-school style traps for GURPS, my advice is to keep in mind that they don't really act like much of a resource attrition as they do in D&D-based games. They're much more of a threat coupled with actual active threats. Because of this, it's worth mixing in both unattended traps and attended ones. This way PCs have to treat all of them like a combined-arms attack by foes with a dangerously slanted battlefield, which adds to the fun of dealing with them. If they don't, they'll get caught out by foes waiting for the trap to spring - which also adds to the fun of dealing with them.