with smalltalk, i can write a test, have it fail and from the debugger, add my needed classes, add instance variables, change variable values, check state, move back to previous points in the stack and restart after making those changes and continue on my way. once you've tried it, it is a very addictive and pain free way to develop. just doing dynamic typing doesn't give you that. it requires much more, in the end that is what really interests me. i find that to be far more of a productivity boost day to day than the stuff that these static vs dynamic arguments usually turn on.
As to people who stick to a single paradigm and tout it as the best thing since sliced bread well... except when I get a little cranky I don't have much use for that and try to tune it out as background noise.