I only have a hand full of brews on my G40 so far, but I find that the brewing process is quicker, but the clean up process is longer than my old propane 3 vessel system. Including cleaning, my total brew time is about 5 hours if I do a 1 hour mash and 1 hour boil. Of course, I'm still learning my system.
I expect my brew day can get significantly shorter if I remember to fill the G40 with water the night before and set a delayed timer to warm up the strike water first thing in the morning so it is ready when wake up. It would sure be nice to wake up, add the milled grains to the G40 and then go about showering, brushing my teeth and eating breakfast while my mash is going on. This would let me finish the brew day long before noon and have the rest of the day for other things. I plan to give that a try this Saturday and will report back.