A S&W hammer block can break just as easily as a Ruger transfer bar, so both designs are roughly equal in that regard.
That's news to me. I'm interested where you got that bit of information.
I've haven't had, or heard of a Smith hammer block breaking. It isn't a part thats even stressed, unless the gun is dropped on the hammer. Transfer bars are stressed every time the gun is fired or dry fired.
"Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat." -Theodore Roosevelt-