Graphite might be a good alternative as well...

This sample was free...if you contact Dupont, they might still send out a slug or two.

Went for over a year without a clog on my stock SD Hotend; until it failed in the midst of some heavy print jobs of course!  Luckily, I had purchased a spare when I bought the SD2.  Replaced it and started to unclog the old one.  Worked out OK...all clear and clean.

Then I started reading up on PEEK and comparing it to some other material I was familiar with: Vespel from DuPont.  Vespel is a thermoset material which has a capacity to work at 300c with no effect on mechanical properties (threads).  So I decided to try something...

I had a plug of the Vespel which I got years ago as a sample to evaluate in bearing applications...Being the pack rat that I am, I dug it out and made a new "stock" hotend!  I could have just machined the Vespel only and used a stock threaded barrel, but I wanted to try a 2.0mm bore instead of the 3.0mm.  So I made a new barrel from scratch as well...see photos and progression below:

Threaded barrel from scratch:

New Vespel replacement for PEEK Insulator:

And the final assembly:

Have not tested it yet...I'm still running a string of prints for a hot job; but if it works as planned, there are 2 main benefits:
Pros:
- I can print at higher temps
- I don't lose any print height since the Hotend is not any longer

Cons:
- More apparent moire due to condensed melt chamber diameter

Wish me luck...The moment of truth still awaits!