Sorry for this patchwork thread, I should delete all posts and write a conscise tutorial instead, won't have time to do that before weekend.
Tested the rack today with 342kg, no problem at all. I would have put 500kg on the bar but I ran out of weights in my barn. Will repeat that test next weekend and place also my two 24kg and my 40kg bell my 16kg bell all my small plates and probably also my dumbells on the bar. That should be ~500kg. Pretty confident that the rack will do just fine.
They are still not finished, two support structures need to be added, basically two wooden X's, one directly under the top plywood/multiplex plate and one at the lower frame. These will reduce torque to an absolute minimum and increase the breaking strength of the top plate considerably. Decided to build three extensions per rack, 50mm, 100mm and 150mm, which makes the rack adjustable from 1000mm to 1300mm in 50mm steps. Each step can be used for depth jumps, box jumps etc. as well. The rack will get a good paint job so that I can store them outside when I finally get one of Sumo's 2/4 racks.
It is suprisingly easy to load the bar, and there is definitely no risk to loose a finger when you re-rack the bar.
BTW if one doesn't mind the look they make for good cocktail tables for a garden party, too.