I would not at all be bothered by the level of security between FID and TID, let alone we were never informed how Apple reached the quantitative conclusion of 1 in a million vs. 1 in 50,000, etc.
The total security level of a device is determined by the weakest link in the various security chain. What about the possibility of somebody being able to hack into a passcode? What about the vulnerability of email password and credit card info saved in the device. I cannot immediately come up with a list of security vulnerabilities that is less than 1 in a million etc (that value alone is a mystery anyway), but I know there are many security vulnerabilities in any iPhone.
So, I am not bothered at all by this security issue but more interested in a level of convenience between the two. I use Apple Pay a lot (I am in Canada and you can use Apple Pay in a rundown Chinese food place in a small town, way out of place. For that, I prefer TID. But that does not mean I am not interested in FID. I am totally open-minded. But if I am going to buy an iPhone with FID, that is certainly not because of FID. My daughter bought an 11 Pro, and am (supposed to be
getting feedback from her. I am currently using the 8.