No neck issues AFAIK, it's not like I stay in one position for too long.

The configuration I end up using the most is with the laptop sitting flat on the floor, one foot resting planted next to the laptop, chin resting on that leg's knee. That side's arm snakes under that knee toward the keys. The other leg is tucked in like cross-legged, other arm's elbow barely touching that leg's calf, straight to the keys. This setup puts my chest against the thigh of the upright leg with the chin on it. It's a super relaxed configuration, and I'll just alternate which knee is up vs. tucked in periodically.