I'm building a slab table from 3" thick redwood slab. Top is 40" x 72" x 3". Legs are 20"w x 27"h (plus tenons into top) x 3". Currently, the legs are cut a bit long to 30" and I was thinking of tenoning into the top with 2" tenons. The attached article lays out pretty much exactly what I had planned to do, but I'm concerned as to whether this will be suitable for a large heavy table. I've read that a table of that weight should be knock down. If so, I was thinking I'd forget about tenoning into the top and use two stretchers on top near the ends rather than one down the middle.
http://www.wwgoa.com/articles/projects/slab-top-bench-project/
Any advice would be appreciated