I think I learned and progressed as a rider the most once I discovered both Mildcat and Wildcat. Makes me think I'm due for a Sourlands trip--its been a few years.
Yea, I'm good with the going down part with that stuff, I just struggle with the up, mainly because of technique (power pedal stroke timing, step-ups, etc). I'm better with roots, but rocky ups I struggle with.
For rocks practice, I'd say head over to Lumpy Bumpy at Allamuchy North. Instead of running it end-to-end, just stall in the middle and hit the features from different angles. You should be able to test any size and slope obstacle you need there.
Fugawe Fridays. If pedaling in tech is what you need, then Fugawe is the spot. By far the slowest average speed in any of my rides. Hardly any reprieve from constant rock smashing. If you need test your limits there’s plenty of slabs and gnarly DH. To ride Ersberg clean is any tech riders life goal.