I run the 50/37 with 10-26t on the back and find it feels great, with good spacing and excellent range in gearing. Add in some bigger pulleys and the efficiency ‘loss’ of the 10t goes away! haha
I rode the Kona course in 2006 with a 48/34 and 12-25 in the back. I basically never took the bike out of the big ring other than on Palani getting out of town. When I “spun out” I just got into a Sebi Kienle tuck before Sebi was doing it coming back from Hawi and on zero watts was passing all the guys pedaling like crazy sitting on my top tube :-). I just had the 48 tooth back then because locally I have a lot of rolling hills and I hate going back and forth, so I wanted to just stay in the big ring (it was also when larger cassettes were not so common).
Keep in mind that Jacques Anquetil won several tour de Frances on a 52x13 large gear (that’s the same at 48x12). Most of us are not riding faster than him on all our new tech. The large gear thing is somewhat overrated. It is not totally overrated, but it is less important than most of us think. A good zero watt tuck often can get us close and the benefit of the zero watt tuck is those joules are saved for later, meaning we probably can ride other parts of the course faster using up some more joules on uphills rather than using up a ton of joules to heat up the wind going fast. There is a massive energy cost of pedaling hard at high speed when you can pedal “not at all” and go almost as fast.