To be clear, the Weber Genesis grills are well built and very efficient, but efficient enough to provide high temperatures and fast preheat times with only 75 BTUs per square inch? The new version has a thinner cast aluminum firebox, but basically the same design. This means a small vent space along the back and a lid that closes tightly.
To test the differences I set both grills side by side on a sunny, but breezy day. The outside air temperature was around 50 degrees F. Both grills had newly filled propane tanks and both were clean. I turned on the propane tanks and started lighting the burners. On the old design, once the first burning is lit the rest light on their own. With the new design, the burners have been turned around and you have to hit the electric igniter each time to turn on the burner, but I still did my best to fire them up to full power at the same time.
With stopwatch going, I recorded the temperatures on the lid mounted gauges. From the offset it was clear that the older Genesis, with its extra 10 BTUs per square inch, had the advantage. After five minutes it reached 430 degrees F compared to the new Genesis' 370 degrees. After ten minutes the lead was still around 60 degrees. The older Genesis reached 600 degrees F., the maximum reading on the temperature gauge, in 13 minutes, while the new grill remained at 520 degrees. How long did it take the new Genesis to reach 600? Well, as I said there was a breeze that day and after 30 minutes it had managed to reach 595 degrees F. I have fired the grill on several occasions and each time it managed to reach nearly 600 degrees after 30 minutes.
Of course, hood mounted thermometers are notoriously inaccurate so, in addition to this time test I checked the grate temperatures with an infrared thermometer. At 600 degrees F. the Genesis Gold from 2005 had a grate temperature of 830 degrees, while the new Genesis E-330 at almost 600 degrees had a grate temperature of 790 degrees. Both of these temperatures are capable of doing some serious searing, but the question is, how long will it take to get there? Even with the E-330's internal sear burner running it couldn't manage to heat up anywhere near as fast as the old Genesis without the sear burner, but it did get a grate temperature of 890 degrees F., directly over the sear burner. This is an amazing temperature, even if it takes almost 30 minutes to get there.
On the other hand, the new genesis uses less fuel, so less trips to the filling station, but I doubt many people will notice. The simple truth is that gas grills work by brute force. The more BTUs, the faster it heats up and the higher it goes. Poor quality gas grill makers boost the BTUs to show off and then put a large vent space in the back to keep the grill from damaging itself from high heat. The Genesis has always been an efficient grill, but in this new version seems to have taken it one step too far, after all you are not saving fuel if you are preheating an extra 10 to 15 minutes.
Personally I blame Consumer Reports. The people at Weber tell me that the 2011 Genesis has been in development for three years. Three years ago Consumer Reports blasted the Broil-King Sovereign 90 for melting its own firebox during their uncontrolled flare-up test. Broil-King Grills have always been powerful and this model boasted 115 BTUs per square inch. Add to that the drippings of six huge, fatty steaks and Consumer Reports melted the bottom of their test grill (just for the record there was never a reported case of this happening to a consumer). To rectify the situation, Broil-King issued a recall and came up with a retrofit fix for the grill, but after that the BTUs of the Broil King Sovereign were dropped to 98 per square inch. Other gas grill makers have also dropped these numbers and you have to wonder if Weber's own internal testing didn't leave them worrying that Consumer Reports might try to turn their sights on them. Since Weber intended to offer the sear burner as an extra feature on Genesis grills and since it boosts the internal temperature of the grill by more than 10%, they may very well have felt it necessary to cut the rest of the power to compensate.
Whatever the reason the great Weber Genesis of old has become the really good Genesis of today, just plan on turning it on early to preheat.