I did a fair amount of work, including making cams and cam tracks on an R/T, and if you can afford larger, get larger, bearing in mind of course, your expected work, and the size of the machine. IIRC, the ones I worked with were 15 inch tables.
It's easier to do small work on a large R/T than the other way around, and most of the larger tables have better accuracy when dividing out the circles, if you are using a bunch of trig to figure out your start and stop locations of your curves so they blend.
Pay attention, no matter the size of the R/T, to your built up height, if you need to add a chuck on the table, AND mount the R/T on an angle plate to get the results you need, you can get really tight on head room to work in... That aside, almost all the rotary table work we did was directly mounted to the R/T's own surface, with at most, a layer of sacrificial material between the R/T and the work. By carefully clamping parallel bars to the table, offsetting them with gage blocks, and re-clamping the work after it was moved, we could move where the center of the axis of rotation was, as we required.
Along the lines of what was mentioned above, rather than worrying about how to deal with the weight later, fix that crap now, and set up a hoist, or acquire a hydraulic table capable of reaching to the level of the mill table, so as to avoid destroying your back any sooner than you must. Got the pins in my back to support this theory, too!
