Fold-Flat 3-in-1 Workbench

I needed a surface to work, the bench on the wall is just not without occupants long enough be useful, but I needed something that I could stash away against the wall. I found the projects on LJ, which led me to this link:

http://www.woodstore.net/plans/shop-plans/workbenches/598-Fold-Flat-3-in-1-Workbench.html

It was a fun build, really got to use the planer alot which is an oddly satisfying tool. Also, have since integrated SPAX t-star screws into everything I do. Wish I knew about them years ago.

My review of the table is-

Positive
-Super heavy duty, laminated MDF is no joke
-Flat as Oklahoma
-portable is useful
-nice as an outfeed table

Negative
-i cant get it stable enough for my liking. seems to wobble too much, even with added leg braces
-I picked not heavy duty enough casters, is HORRIBLE to push around, will need more modification
-the legs dont stay in a closed position when opening/closing

UPDATE 6/16/2015
I uploaded 3 pictures of the final modifications to the table. The casters were total garbage, I replaced them with these from a Black Friday sale. Getting the base to rest on the floor was key for stability. NOTE: this required shortening the legs, redrilling the t-nut holes and reinstalling the leveling guides. I also added one of these braces for each leg to solidify the extension position of each leg. Lastly, I tried rare-earth magnets to hold the legs up when folded, that was a no-go. I went with one of these for each leg. They do a nice job of grabbing the legs tight when closed, and they stay out of the way when the legs are open.