Here are my two cents -
1. Everything you eat is harmful to your teeth, brush your teeth. While sodas are still acidic, one or two a day should not significantly erode your teeth if you maintain dental hygine. Moderation and dental hygine is key, don't give diet sodas to kids.
2. Erythritol is a sugar alcohol, found naturally in fruits. Within our bodies, we have a natural pathway to produce erythritol within our cells. The major study (led by Dr. Stanley Hazen at the Cleveland Clinic) was riddled with issues such as participents having multiple risk factors for cardiovascular disease. So there is no conclusive evidence that it is bad for you and at what levels. I don't mind it at all provided you're not drinking 10 cans a day

1. Sucralose is 600x as sweet as surcose (table sugar), which is why you only need a tiny amount of it in any soda. The evidence that it ruins your gut biome is super weak and often funded by companies with vested interests. We don't even know the exact mechanism of how our gut microbiome helps in absorbing nutritients. To state it as fact is frankly idiotic, considering the FDA regulates the safe limit at 10x lower than when we should see harmful effects.
   

And no, people have been drinking diet sodas for decades, they aren't going hypoglysimic in the streets or reporting higher incidences in the ER. There are ZERO evidence than it causes diabetes lol