reible wrote:"...I think it is safe to say that a hand held router with the right jig or a table mounted router with the right jig can do all that a OPR can do. It is just a matter of how much thinking and effort you want to put into making or buying jigs..."
In the above quote, Ed said my opinion better than I could have. He gave you the whole answer in just two sentences. I'll try to add just a little color (more verbose!) At least I can add perspectives from my shop.
Did you see, in that other forum, the extent one guy went to to build a "slot router"? He even had a slider with 8 wheels! A long time ago, I did slot routing with my SS in horizontal drilling mode. Someone, I think Eric told me on this forum to use a spiral bit for this and it worked better than a straight bit. The point is, slot routing is nothing special for the Mark V, and the OPR makes it even easier.
As for Shaping: I bought a set of door panel shapers from Shopsmith some years ago. Have used the set with good success in the SS shaper mode. Other than that - have used the shaper with various bits to shape the inside and outside edges of picture frames. This worked great! I have always taken small bites and have had no problems with the bits of with the shaper. The Shaper/Drum Sander Fence (555113) that came with the purchase, does not adjust easily for me. My problem is with the round screw adjusters at the rear of the fence. So, I just leave it flat (both sides even) and adjust by loosening the bolt down screws and tapping one side forward or backward. The good parts are - the shield is safe and - the vacuum from beneath works well! In my opinion, routers cut easier (smoother) than the shaper. This is most likely because of the speed of the bit edges. I'll continue to use the shaper mode when the case presents, but for mortises and tenons I believe I'll use the OPR.
The biggest single advantage for the Overhead Router when comparing it to a table or free router is - the Overhead Router gives me the ability to see what is being routed. This is particularly valuable to me when doing "stop routing" of any kind and when making a particularly ticklish connective piece.
Case in point of seeing what the router is cutting - When I re-formed the counter bores on my OPR table and the new shop made sliding table - I don't think I would have had the same success with a table or free router. With the OPR I could use the adjustable collar on the SS and move the bit (really the wood) 1/64". (1/4 turn) Pretty fine adjustments!! and I could actually see the adjustments before routing.
I'll also still use my "flip up router table" when edge routing a whole edge. Why? Because it is really easy to set up. All I have to do is lift the router into it's base that is permanently mounted to the underside of the table, screw the fence to the table, adjust by tapping and go.
I now use the same router motor for all router operations. It's a PC 850. It fits nicely into the OPR and of course into the two bases it came with. The changes of the router motor only takes one minute at the most! Oh Yeah! Plunge routing needs will be free hand, because I now can do "under table" plunge routing with the OPR and see what I'm doing!