A big problem is latency even today anything above 3s is unacceptable for mining, half of miners are not validating blocks before starting to mine because it takes to "long", miners spy on other miners and then try to mine empty blocks, Bitcoin doesn't have a lot of orphan blocks today because mining is centralised in China, do you think increasing the block size will help with any of these problems?

One thing is to test on a controlled environment another completely diferent thing is to test on real world.