It seems that indoor, low light conditions are where Stone Lock Pro excels. They use NearIR technology so they require no light to work, however, they perform poorly in brightly lit areas (such as many outdoor entrances). The detection range is also lower or closer than FST. A subject can be no more than 3' away (from our tests...Stone will say 4' max, but that didn't work reliably for us). Admittedly, Stone Lock does not have a true outdoor rated solution. We would have had to 'protect' the reader from the elements in some way if we wanted to use it outside.
Because of these issues Stone was not a good solution here. In low lit areas where the subjects will be close to the reader, I think their solution would be very good.
Subject detection on the Stone Lock Pro was about 1 second.
For FST, they perform better in areas that are well lit, but struggle in low lit areas. They require a minimum of 200lux for a proper facial read. One advantage of the FST solution is the subject distance is longer than Stone Lock.
We had one of their engineers out to the site last week and based on what he saw, he had no concerns on the outdoor entrance. However, we do need to add light to both the front outdoor entrance and the garage entrance so that at night there is enough light for a proper read.
We should be able to get a good read about 6-7' from the camera which is much more realistic for the front entrance.
We were able to take some shots in the vestibule, but not directly outside...but the engineer was not concerned with it, so I'll take them on their word for now.
To answer your question directly, if conditions were such that the Stone Lock Pro would work correctly, I would likely choose that solution over FST. I personally like the NearIR (non-photo based) solution better. Detection was a bit quicker (Stone = about 1 second, FST = about 2 seconds).
However, that is not to say the FST's solution is not good. It seems to be very good, just different.
I don't think I'll know how well it does or does not work until we actually deploy it and begin registering residents and seeing how it performs in real life.