If you really
love your tools right now, don't switch.
I would suggest learning something else, though (I chose Grails a few years ago), because at the very least it'll give you a new appreciation for your toolset. You'll understand the strengths more, you may identify some weaknesses (either inherent in your tools or how you use them) and start to think about how to use your own chosen tools better.
I split my time between PHP and Grails now, for the most part (some occasional other work) and knowing both I have a better idea of how/when to use specific approaches.
You may end up hating your PHP toolset after a while using something else, because you'll start noticing how verbose PHP makes some tasks (using a framework like symfony can sometimes reduce that). Or you may recoil at how ugly some of the Ruby or Python stuff feels to you. You won't know until you try, but I think everyone should take some time to learn a moderately different platform at some point, if only to help to understand your own platform better.