FWIW, I suspect my mails anyway won't come through the list, since my last request for help didn't came through.
It might be not a big step from 2.6 to 3.0 compared to the steps from KDE3 to 4 and GNOME2 to 3, but there was a big step from kernel 2.6.38 to 2.6.39 regarding to rt abilities/issues, there was a small, but important step regarding to ALSA, since a professional card switched from PCI to PCI express. There might be some big steps regarding to things I don't have knowledge about too. It's very relative what's a big step and what not, regarding to abilities and to things that are dropped.
Sometimes you don't need a patch. E.g to join ALSA from 2.6.39 with a 2.6.38 or older kernel, you also could compile ALSA packages, instead of patching a kernel. Of cause, this depends to the kind of fixes/upgrades.
OT: I suspect that I need to pay a company to recover data from a disk, since recovering data from ext4 seems to be impossible by Linux tools and I couldn't find information how to do it using a disk monitor, but I'm sure I'll switch the distro and the FS. So just 2 cents, IMO Arch Linux could be a better choice for people who usually used Debian testing. I lost data when I again needed to restored Debian testing from a backup. It was my fault that I lost the data and I had really bad luck, since originals and backups where mounted and deleted from ext4.
Anyway, especially regarding to kernel issues, to X issues and some other things caused by Debian policy, at least for me, Arch seems to be the better choice.
If you need very special patches for kernels, you should use Google. I know that there's a Ubuntu based distro, that's good regarding to the patched kernel, for people using CNC machines. I know that regarding to the kernel, Arch does support what I need for audio.
I know that I had to restore Debian testing much to often from a backup.