I switched because the occasional, sporadic nature of that sort of work meant that I often had to get back up to speed with a bit of code with as little difficulty as possible, in as short a timeframe as possible.
I was better at writing Perl than I was at Python, but I could read Python code after the fact better than I could Perl.
I could probably have circumvented it by commenting my Perl properly, and using the long version of the inbuilt operators, but hey. That'd have been too easy.
I did find Python's regex stuff nicer to use than Perl's, though. Which is not what I expected at all.