If you made the plus sign as described, with a generous border around it, say 4 " and your table width were 32" that would leave 24" of cross grain inlay. But with the cross grain inlay mitered at the center, you would have a total of only 12" of cross grain movement to deal with, which a veneer, could most likely handle (especially if you were to use a nice burl as opposed to plain maple), assuming you are using well dried stock for the top. But if it didn't, whatever movement occurred would be purely cosmetic.
If it looked too horrible, you could always take off the table top, run it through a wide belt sander, and still have a nice table top.
That would not be an option if you were using solid material unless you made each edge of the cross grained section of maple like the bread board ends of country furniture.
Plywood would be the best option for stability, if you think the top will hold up long enough and look the way you want it too.