Well, interested intellectually, but yes, I'm an engineer and I judge the utility of tools by their applicability to the work of engineers. That a tool like Coq could theoretically be used to fully reason about and verify a large program is of little interest to me, as no one so far has been able to do that, let alone enable engineers to do that.
BTW, I'm not too sure what the point on SMT was. SMT just uses SAT for whatever theory is needed (and possible). TLA+ uses SMT (as well as Isabelle) extensively as automated tactics in deductive proofs (in set theory), which I have only just started to use. SMTs (and certainly SATs) are not related in any way to one mathematical formulation or another, just like garbage collection isn't. In fact, SATs are commonly used today in bounded temporal-logic model checking.
No. It's medium-sized; and it required a world expert, and it required a lot of effort, and even he had to skip on the termination proofs because they proved too hard/time-consuming, so he just put in a counter and throws a runtime exception if it runs out.
BTW, I'm not too sure what the point on SMT was. SMT just uses SAT for whatever theory is needed (and possible). TLA+ uses SMT (as well as Isabelle) extensively as automated tactics in deductive proofs (in set theory), which I have only just started to use. SMTs (and certainly SATs) are not related in any way to one mathematical formulation or another, just like garbage collection isn't. In fact, SATs are commonly used today in bounded temporal-logic model checking.