Indeed you can and I had read it before and appreciated the real world data, though you are the exception, rather than the 'norm', in this. A 6% improvement is quite something from one change, if all else is equal, which is why it surprises me that this sort of evidence isn't plastered over the web by shoe/pedal manufacturers. It may be that the benefits are so apparent that they feel no need to demonstrate. But even at 6% I'd have to weigh up the inconvenience aspect and the potential danger of falls etc. I have to accept that your numbers don't lie so either you input more power or you transferred the usual amount of power at a more efficient rate.
My experience didn't reflect yours and I didn't enjoy being attached to the bike. I could be bias, I could have a rubbish pedalling technique, I may have set the cleats/shoes up wrong. B
ut I do feel that these sorts of threads need a balancing viewpoint and I'm currently filling that post