Coincidently, I had rebased Marcin's kernel to 2.6.37. You can find it under "target/linux/mt623x" of this OpenWRT port: http://ac.nl.eu.org/mt623x/
Thanks for information. Wolfram Sang have written me already that he also rebased Sciphone G2 kernel to newest one without issues, so I don't expect problems here. Today I'll commit rebased kernel to OsmocomBB repository.
BR, Marcin