I've used the eggbar vice (the round race model) and liked it some. PROS: The on edge grip took getting used to and isn't something I use a lot so didn't get the hang of it. The grippiness of the platform was excellent. The ease of attachment to the bench (no strong arm required) was nice. CONS: the race model doesn't hold two skis at a time and in my production environment, skis side by side makes work quicker and easier. I simply swap skis left and right without having to move them off the bench.
I'm waiting for Ace to send me a shop model that is reportedly quite nice, two skis/one snowboard wide and with an easy to adjust length between the stands.
I use an old set of Swix vises. Narrow so not optimal for fat skis. Despite the center clamp, wide skis wobble as the clamp often won't hold the non-vertical sidewalls.
The 2x4 arrangement on top of the bench holds the second ski while working on the first. Time and space dictate that I not move the ski not being worked on around to a wall or rack, but rather just swap them.
The tray is held on by the vise clamps. Just mount vises on the bench with clamps loose, slide the tray in place and clamp the additional cross pieces to span the slots and permit the clamps a tight grip on the bench.