[normalmutant]

Two important things:
-The crates are a lot smaller than they look
-The ramp has only about a 20-degree slope

Also, to answer some of your questions,
"How easily can the magnet sensor detect the magnet balls?"
Last year, with the PVC pipes, it was difficult and often unreliable. We used different magnet sensors.
"With a most of the balls on the field, how many can a good collector grab in a minute?"
Idealistically, lots. Watch some videos of Hot Shot to get some ideas.