Once you've got a load of 28mm holes drilled in them you won't want use ordinary clamps even my carvers which i used to rave about don't get used much nowadaysThey are good but I'm finding it pretty annoying not having box section around the edges which was easy to clamp to. Tables like what @sako243 has posted only have a small lip around the outside and its as-cast.
Still on the lookout for tables like @pressbrake1 had last year with all the holes in them, out of Fords if I remember correctly.