Wingmans stand is nice, my reloading bench way back when, was of similar construction except mine was about half the length of his...very strong with the 2x6s i used. I revised this a little when i lived in CT for work benches which i would incorporate into any future reloading benches. The top would be 3/4" MDF with a single sided, 1/4" plywood on top...painted all with a good like cement floor paint.
The reason i went with solid top was i didnt like the edges of the 2x6s, wanted complete smoothness...the 1/4" was used for like a veneer...i always one way or the other, eventually trash my bench tops...so when they get trashed enough, i can simply add another 1/4" sheet on top, or remove the damaged one and replace.
Dont know if wingman did or not, but working with lumber like this for benches, i always glue all pieces together, and double lag bolt everything in the stand...nothing i hate worse then a wobbly workbench. Wingmans looks pretty solid.