I originally tried single jacks, but with only one pressure point, the extension system wouldn't stay straight in the tracks and would bind. The dual jack system has a few advantages:
-Higher weight capacity (as if I'd exceed that anyway)
-Simpler track system
-Leveling ability: This is the BIG one. I can fork lift these tables out onto our concrete yard and level them really precisely because I have a jack on each corner. With a single one, they just raise or lower the whole side at a time.
Totally agreed that the system is a bit overkill though.