To answer your questions. With regards to use, I haven’t been real disciplined about recording the exact amount of filament I’ve been using and a lot of the filament I have is also in a partial state of use. So if I count up the empty spools since I first first installed that tube, I would estimate that the wear you are witnessing in the photo is roughly between 20-25 rolls of PLA, 7-8 rolls of PETG and 3-4 rolls of PC.
On the subject of the extra PFTE, yes, I purchased a fair amount of it for exactly what you described.
As far as the wear pattern goes, I followed Bambu’s guidance and that’s the reason I posted it this originally, to ward people off of following the out-of-box recommendations when using this kit. They gave out bad advice in my opinion.
I also reattached the original coupler on the back which, in their instructions, Bambu specifically directed you to remove when you upgrade with the through-hole tube grommet for the chain. The chain was the main reason for my upgrade, I did not like the tube rubbing up against the glass and sides, it just invited unnecessary wear.
I believe this method pictured below is much more sound. One can’t avoid wear and tear on the feed entry. However, isolating that wear onto the original pivoting feed component means only needing maintenance on a 20mm-30mm of tube rather than the entire length since the entry point received the brunt of the wear.
As for the wear pattern you saw, yes, they were definitely not uniform wear. Had I been supplied with the correct length to start with, I would have simply snipped off the end. That tube certainly would have survived a 100+ more spools. The wear was confined at the very edge of the input tube where it had the most amount of friction upon filament entry. Note that I’m not tossing that tube, I will simply cut it into lengths and use it for the sacrificial segment you see in the photo.
With regards to the side mount spool. I don’t favor such a solution for my use-case. I have the good fortune of having access to 3 sides of the printer in my office so it is by far much easier to access the rear than the side. Having said that, the skins I put on the P1P were the pegboard skins and I did print a set of side spool holders but that is used solely for momentary spool swaps so I don’t have to leave the other spool lying about.