In my opinion LH Business class is nothing special, and I certainly wouldn't switch airports for it. If the option was LH J vs. UA J I would just take United.
It might be easier for you as well, connect thru EWR, and the IAH-FRA nonstop might open up later on.
The problem is, this one of the shorter itineraries for my journey. The only shorter one is IAH to BOS to TLS, which is $15 hours and 45 minutes instead of 17 hours and 30 minutes. Every flight is using Lufthansa for the business class portion exception for a few select itineraries using Aer Lingus or Air Canada, but those options are over 20 hours.
I've never flown an A380 in general in business class. I've heard it's a lot quieter and the flight is a lot smooth, which are two of the main reasons why I am looking into the route.