I used Petrus and I wanted to switch to Fridrich.
And I switched.
Seriously, does it matter what others do? Find what you like best. I have my pseudo-scientific reasons to believe that Fridrich is the best method for speedcubing. Just because it's getting boring doesn't mean you should switch. Instead, consider practicing other methods in which you're interested to, say, sub-25, and still maintain your Fridrich speed. It's not that hard and you don't really have anything to lose.
I can consistently sub-30 Petrus and Roux, and almost consistently sub-20 ZZ and CN Fridrich, not as I fast as I'd like to be, but it's incredibly fun! In fact, from my experience, learning all these other methods actually sped up my Fridrich. I got stuck at sub-17 for a looong time, started to mess around with all kinds of funny methods for a while, and I'm sub-14 now (in case you wanted some credibility).