The XL costs $100 more for cooking-area, but it costs other things too. First, assembly is harder. The XL ships in a heavier carton (~155 lbs vs ~130 lbs for the standard) and the larger barrel is awkward to position single-handedly. Plan 70–80 minutes for two-person assembly vs ~60 minutes on the standard.
Second, fuel efficiency is worse. The XL's larger cooking chamber means more interior volume to heat — that translates to roughly 15–20% more pellet consumption per cook at the same temperature. A bag of Traeger pellets that lasts 18 hours on the standard Westwood lasts ~15 hours on the XL.
Third, the pellet hopper is the same size on both. This is the underrated XL drawback. With an 18-lb hopper but higher pellet consumption, the XL needs hopper refills slightly more often — which is fine for shorter cooks but matters for 12+ hour brisket sessions where the standard might finish on a single hopper load and the XL might need a top-off.
Fourth, the footprint is meaningfully larger. The XL is wider, deeper, and heavier — harder to roll across patio steps, harder to fit through narrow gates, and harder to store in a covered area. Measure your space before assuming the XL fits where the standard would.