Do buck-boost transformers present a safety hazard usually associated with autotransformers?

No. Most autotransformers, if they are not of the buck-boost variety, change voltage from one voltage class to another.

(Example 480V to 240V) In a system where one line is grounded, the user thinks he has 240V; yet due to the primary and secondary being tied together, it is possible to have 480V to ground from the 240V output. A buck-boost transformer only changes the voltage a small amount, such as 208V to 240V. This small increase does not represent a safety hazard, as compared to a buck of 480V to 240V.