The one in the photo looks very similar to a 8" Palmgren XY rotary table I sold for a friend. The size and brand name of the RT in the photo is not stated by the original poster. The one I sold was new in the box, NOS from the 1960's, looked beautiful, but was not at all rigid, and was lightly built. It would only be useful for light work, in my opinion. RT's like that are more suited for a drill press than for a milling machine. The XY is not needed on a mill, the additional height due to the XY steals headroom, and the additional slides make it less rigid. It could make a drill press into a very light mill for doing light work, like with plastic, and perhaps light work with aluminum. These comments only apply to the one I sold, I have no knowledge of the brand and size of the one being discussed in this thread. I never tested the one I had while cutting anything, just my opinion based on inspecting it and cleaning it up a little...
Edit: FYI, the one I sold, NOS, maybe 15 years ago, went for $350 for my friend. I would certainly not pay that much for it...