> In Javascript (which is also dynamically typed) I've had a few times where adding 1 and 0, say, yielded "10" because either the 1 or the 0 originally came from a string. OK, I can live with that, but I find the fact that you can use that string in numeric comparisons potentially confusing.

There are two problems demonstrated by your example; the other is the overloading of the + operator as a design decision in JavaScript. Easier, but worse.