I am looking at replacing my Harmony One because I now have a need for RF control. I have it narrowed down to (2) Harmony's. The Harmony Ultimate Home (915-000237) & the Harmony Ultimate (996-000120). There are a lot of bad reviews on Amazon on both, but nowhere does anyone talk about the differences. They both seem to control up to (15) devices, they both have a cell phone app & they both seem to be RF capable & have a Hub that comes with each. The Ultimate Home is the only one still shown on Logitech's website, so could it be that the Ultimate is simply a previous model? Any help here will be greatly appreciated so I can pull the trigger on getting one coming.

They are identical now. The old Ultimate is a previous model and used to lack the ability to control home automation devices like the "Home" model. But they have since added that capability to all Ultimate hub based remotes via a firmware update. Sounds like you aren't doing any home automation anyway (lights, thermostats, security systems, etc.). If your old One has a swollen battery, Logitech may replace it with an Ultimate for free.

Not sure what you mean by swollen battery. There may be a meaning there I'm missing, but if not, again, the only reason I need to replace the Harmony One is because of it's lack of RF capabilities. Plus it has started to become sluggish.

Swollen means the battery has degraded and increased in size to the point it cannot be removed. This is considered a safety hazard. So Logitech will replace the entire remote even though it is out of warranty.

Remotes don't become sluggish due to wear or age. Something else is causing that.

Replace it for whatever reason you want. I was just suggesting the free option in case you weren't aware. If you like spending $300 on remotes, knock yourself out.

What contact method is used to try for a replacement? I also have a One and it is not only getting sluggish, the remote lights no longer come on from when it is aspleep when I move it around. I have to make circles with it and move it all around. Annoying.