I'm partial to the Jandy heaters as I am a dealer and have installed their heaters for about 35 years.

The Jxi model is probably the nicest heater they have made to date. It's compact, it's sealed well to keep critters out, it's lightweight and it has a small footprint. Your LLG is giant compared to the Jxi.

Since they came out about 5 years, we have had zero issues on installations.

There are 3 models: 200, 260 and a 400. They still have about same efficiency as your old model-roughly 83%. Electronic ignition means no standing pilot and a fan assisted exhaust vent.

It's fully capable of working with Jandy's RS automated systems.