Steve,
Thanks for filling in some of the details. I'm not sure your slam of anyone not using Nippon Kogaku is accurate, as the predecessor to CPS used to regularly show up at many of the motorsport events I went to in the '70s, and their motor home was plenty busy with folks using their services.
This topic has been discussed several times, but to summarize:
The entry price for the converter is high, but with FD 300 f2.8L lenses going for way less than $1000, there is a savings there (A used EF 300 f2.8L goes for around $2500). Add an FD 400 f2.8L for $1200 or less and the savings is better yet ($3500 or so for a used EF). Both of those FD lenses have the same optical formulas as the initial EF version, and the TC factor of 1.26x does not impact the IQ - but it does take away one stop. Manual focus is required, but for exposure the FD lenses will work in either Av or P mode as well as M.
The FD lenses that work with the Canon converter regularly appear on eBay - that's where I got most of mine. While I wouldn't buy the converter just for the 200 f2.8, once you make the plunge you can add one to your inventory for around $100, and get a 250mm f3.5 with great IQ.
I guess its all in your perspective. I make them work for me.
Have Fun,