My company also uses Smarty, but we're planning to move away from it. (Currently evaluating Mustache.php)
Smarty's parser/lexer is horribly slow. The 3.1.x branch has caused problems for us, such as corrupted compiles and broken nested blocks [1]. As evidenced by the article, the developers don't seem to know what they're doing. You should see the workaround for people with custom error handlers -- registering another error handler on top that checks the source of the error against registered template and cache directory paths!
sounds about right. I don't think anyone would choose Smarty for actual technical reasons at this point. I personally think plain PHP makes a far superior templating system. Smarty is slow, doesn't "protect" designers from any complexity because it's complex itself and is yet another thing to learn.
My guess is that whoever wrote the framework just heard about Smarty while in university, long time ago.