I wasn't sure which to get after I found an inexpensive used FCB on Craigslist. They weren't too much, so I ordered both. I ordered the Uno on the 6th, the Eureka on the 7th. On February 8th, I was notified the Eureka was shipped, I got it on the 10th. Nice!
I plugged in the EurekaPROM and it does everything it's supposed to do. It's a heck of a lot better than programming the FCB myself.
I still haven't heard a peep from the UnO4Kemper people. But, they do have my PayPal payment.
If you're on the fence, go with EurekaPROM. At least you'll get what you pay for.
[EDIT]
OK, so exactly the day when my impatience got to me, the UnO4Kemper arrived. Perhaps it took a week longer because it came from another country (Belgium). It did arrive in a reasonable amount of time. Now, I have to figure out if I want to open up the FCB again.