You are asking this question on a very Perl-specific web site.

I suggest that you should not try to typecast yourself as a <<Perl>> (or anything else ...) Programmer.   Nearly all of the time you will be working on an existing system that might have been started in any one of several languages (and, versions thereof), and which might now consist of more than one (on both the front and back ends).   Once a course has been set, it does not change.   But, in terms of what your career might consist of, exactly which course it is does not matter too much.   You will be involved in a number of different projects, every one different from all the rest.

“Pure <<whatever>> ...?!” ... (Chuckle, Guffaw ...)

Versatility, willingness to accept (and to master) whatever language(s) you find, good diagnostic ability and great teamwork skills.   Those are the most important.

Regardless of(!) the language(s) being used, the role of a systems administrator and that of a software developer are quite different, such that in my experience many people who “see greener pastures on the other side of the fence” often return to where they came from.   Most developers actually do not have a guiding influence on the projects they are associated with:   they fix a lot of bugs and, when they actually develop something new, it is to fulfill a very narrow and precisely-worded change order.   They know exactly what their next year is going to be.   Whereas a systems administrator ... yeah, he provisions a lot of machines and answers the phone a lot ... has a job that is much more reactive.   You should spend a lot of time talking with people in your organization who now hold the job that you are considering.