Testimonial in favour of noodles/inserts.
noodles/inserts may not make you faster, but "run flatting" them down to 5 psi in the rear won't make you slower either
I did the Merritt Crown 120 km XCM in September
Lots of arrowhead like rocks and lots of punctures for many people.
In the first minute of single track, the guy behind says "you (me) have a flat, I see sealant spraying".
I was using Pepis Rokline yellow noodles, with Racing Ralph 2.25" and 22mm id rims. Since it was the start of the race and I had no trouble following in line with a rear soft tire, I didn't bother stopping until the single track finished before checking and sure enough my tire went from 15 psi (as measured at the start with a big brass gauge) down to ~5psi (pinch test), so I got my quick fill and tried to do only a partial refill to get back up to 15 psi, but messed up a bit and only got to about 12 psi. Anyway with the noodles I didn't have much tire squirm as the Pepi's round noodle squishes down into a light-bulb shape between the rim flanges, and makes the tire near impossible to unseat.
At the Merritt Crown, the course was only partially marked and everyone was required to download the course map from TrailForks onto a device, and most of those that used Trailforks to record their ride also downloaded their ride to the Trailforks website, which includes leaderboards for the individual trails that are part of the course. So almost an Enduro within an XCM.
I did two of the four black diamond downhills at 12 psi down to 5 psi (as I was gradually getting more micro flats or had lost some more air immediately after using my CO2 before the sealant worked). So looking back at the Trailforks leadboards, I was 5th overall for the first black diamond dh (Burn & Windy, which is bermy) at probably 10 psi average, and 1st for the second one (Godey, which has lots of rock gardens, rock slabs, root nests and bridges, but not that steep and no berms) going from about 10 psi to 5 psi by the end. I borrowed a foot pump after Godey at an aid station, and the next black diamond dh (Ridge) my tire felt too rigid at ~20 psi. Maybe the extra cushion on Godey made me faster on the dh (I was still slow on road climbs, but according to the speedo on my Garmin, I was no slower than normal on the paved climb between trails)
With Pepi's noodles even at 0 psi, you would have to do something extremely violent to unseat the tire while riding, and at 5psi I have not been able to burp. Although, at that pressure how could you tell while riding. But after the Merritt Crown there were not dried sealant stains around the beads or sidewalls, but over 20 on the tread of the tire. Actually, lower pressure normally prevents punctures from arrowhead like rocks. There are videos out there showing a truck tire at different pressures rolling over a bolt welded to a plate (like a dull spike plate) and at low pressure the tire folded and absorbed the bolt rather than fighting it and puncturing.
https://www.youtube.com/watch?v=9Kz8mmLkeks
The Roklines start round and rattle around inside the tire after mounting, but mash down into the rim after some rough riding, filling up all the rim channel space, and mushrooming up over the beads, effectively locking the tire to the rim
So the "run flat" ability saved my race and enabled me to have an encouraging result, at least as far as individual trailforks segments go. So as far as any measurable benefits or detriments, noodles are still a benefit as far as the "run flat" ability.
I have weighed the Pepi's Roklines after a year of abuse and they didn't gain weight (still 100 gm). They have a shiny exterior that doesn't absorb liquid and is meant to reduce friction between the noodle and the tire carcass. They also haven't been damaged by "Run Flatting" them.
I haven't run flatted a front in a race, but have ridden a front home at 0 psi (mix of trail and road), without damaging tire, rim or insert
With the noodles I have gone from 2.35" tires with 26m id rims (without noodles) to 2.25" and 22id (with noodles) and saved weight overall (some pretty inexpensive narrow carbon rims out there now too)
