I have now put 2300 km on the Compass Babyshoe Pass EL, a 42 mm 650B tyre by Compass Bicycles Ltd that's made by Panaracer.
Being able to use a wider variety of tyres, especially faster supple ones with more air volume, has been a major attraction for purchasing my Elephant NFE. I wanted to be able to run at least 38 mm wide with mud guards. The Grand Bois Hetre and the Compass tyres were getting good publicity and I was keen on trying those (besides the 650B tyres that I use on the NFE, Compass also sell 700C and 26" tyres that are otherwise very similar to the 650B/27.5 inch ones).
While the Velocity Blunt SL rims on the wheels that Tim (GS Astuto) built are tubeless-ready, the BSP and BSP EL are not certified for tubeless use by the maker, unlike some of their other recently released models (650Bx48 Switchback Hill, 26" x 2.3 Rat Trap Pass). The Grand Bois Hetre, which is very similar to the regular BSP (non-EL), is readily available in Japan but also not certified for tubeless use.
Compass Babyshoe Pass EL (650Bx42) front tyre after 2300 km:
Compass Babyshoe Pass EL (650Bx42) rear tyre after 2300 km:
As you can see from the images, the tyres are doing quite well with regards to wear for the distance. I expect to get at least as much distance out of them again, matching the 5000 km change interval I've maintained on the Primo Comet 451-37 tyres on the Bike Friday (i.e. two sets of tyres a year at my 9000-10000 km annual average).
Initially I wasn't ready to go tubeless, reasoning it was safer to change one variable at a time than to jump in at the deep end of technological change.
Messing around with sealant and regular top-ups didn't appeal to me, as well as the prospect of replacing a tubeless tyre with sidewall cut by the roadside without access to a compressor or high volume pump.
But the last argument does not really hold water - you can usually install a tyre boot and a tube, which would be no different from a similar incident with a regular setup with tube. Until that happens, chances are the tubeless setup would have avoided a couple of minor punctures already, by simply using sealant, which works best without a tube.
So If I switch to a tubeless setup, I could basically gain the benefits of tubeless (no friction between tube and sidewall, automatic sealing of minor punctures) with no real downside in the event of a major puncture. The only problem is, none of the top three major tyres for suppleness of casing and air volume that still fit under my mud guards are certified for tubeless use.
The point was brought home on my most recent brevet, the third on my Elephant NFE, when I punctured 387 km into the 403 km ride, due to a glass shard that penetrated the rear tyre. As it happened I just about managed to get a spare tube installed, the tyre re-inflated enough to ride and the wheel reinstalled to be able to hobble the final 16 km to the finish line to complete the event a mere 4 minutes under the 27 hour overall time limit.
When I fully inflated it at the goal with a full size pump to 3.5 bar / 42 psi, I found I had only pumped it up to 1.5 bar / 20 psi which explained the bumpy ride. The tyre hadn't popped enough to be fully seated all around. I really need a decent new pump for the NFE!
If sealant could have saved me this ordeal in bad weather and low on time, I would have been a very happy man.