You posted this a few weeks back, don't know if you're still out there, but...

Yes, both are owned by the same company yet both remain seperate Manufacturing facilities. It's really only paper work that binds them.

The H&G IMO, is the better unit. You will be much more pleased with it due to it's look. A better burner has gone into the 550 which will give you a more realistic flame. The one benifit on the Htltr is they are much easier to service, if it should ever have a problem (Htltr has the fewest warranty claims in the industry!!). The 550 also has a broader back side which gives a better veiw and a has a nicer log set than the Novus.

As far as the battery back up... The Novus has a standing Pilot so it does not need any voltage to start in a power outage where, as you said, the 550 you will need to add Batteries in such a case due to its IPI system. However, by not having a constant pilot burn, you save more annually on Gas than a pack of batteries would cost.