In the picture of the wheels, you may have noticed that the center cap style is different. The "Summit" center cap is a nice, chromed plastic, dome (on the right). The "Vision" center cap is the boxy, "Vision Wheels"-stamped, version on the left.
Just got off the phone with the fine folks at Summit.
I made a deal with them that they couldn't refuse. If they credited me for the ~10% difference in wheel price from the day I bought them to the next day, I would buy the replacement center caps myself to make them all similar. So I have new center caps on the way (~$10/wheel) and a little extra credit from the leftover.
And for future searches, here's the skinny:
Summit and/or Vision Legend 6 Wheel center caps dome with no logo are Summit P/N# VSW-C141 and Vision P/N# C141 or C141-C-CAP (Seen both of those)
Old Summit Cap:
New Vision Cap: