Rolling Computer Table

I recently purchased a new computer and wanted to put it on a compact movable table. I didn't find any commercial computer tables that were exactly what I wanted, so I designed this knockdown, rolling computer table.

The shelves are maple plywood trimmed in solid maple, and the upright supports are solid maple. The top and bottom shelves are 28" wide and 12" deep, the middle shelf is 24" deep and it's 27" off the floor. The selves sit in 3/16" dados, and the fastening hardware is similar to that used in the knockdown desk. The finish is lacquer.

Originally, the bottom shelf did not have the side extensions and there was no middle cross brace. I hoped the weight of the computer would act as a counterbalance to the middle shelf, which it did, but the table was still unstable. Also, the table wobbled too much, despite the dadoes and connector bolts. The 20" extensions on the bottom shelf solved the stability problem, although it's possible to tip the table over when pushing it backwards, and the cross brace eliminated the structural wobble. The table still wobbles a bit, but the movement is all in the wheels.

There are few alternatives I'd try if I build another one:

The dadoes are disappointing. The locator dowel technique used in the knockdown desk works better (and it's used in the cross brace here).
If the front half of the middle shelf folded down, the table would be more compact when it wasn't being used.
Setting the bottom shelf extensions on edge and using spindle-mounted casters so they could be removed would make table more stable when it wasn't being moved frequently.
This table is compact, so the knockdown construction isn't really necessary.