Hi Nelson.
I think it depends on why you want a shaper in the first place. I have a 7" Atlas that I bought for one purpose. Internal keyways. It does a fair job of that as long as you don't get too aggressive and learn to grind the tool. Also longer cuts requiring a long tool bar, say 7", requires that the work be placed too far out on the table and things get a little unstable for my liking. I also use it often for cleaning up rough stuff such as a torch cut before ruining a mill cutter.
I passed on the 16" Cincinnati that I really wanted because I intend to take my machines home before long and it's footprint and weight were a concern for me. If you have the room and can handle the weight I think that's the machine to have.
When I did only one keyway about once a year or so I used the old fashion method in the lathe. Turn the tool sideways in a boring bar and roll it back and forth by hand. Primitive and slow but it works.
Go ahead and get one anyway, they are a neat machine to have.
Doug F.