Interesting, do I get that right that there are two drivers in staging for this USB adapter? A working one from Realtek and a non-working one from Jes Sorensen?
Not correct. Debian is building with the older vendor driver, the staging driver is not enabled in their kernel. LE is building without the vendor driver, and with the staging driver enabled. However, staging = experimental drivers that are still in actively development and/or not feature complete enough to exit staging and be included in the main kernel tree. So the staging driver could be 95% complete or .. 55% with lots still to work on (and I have no idea which).
I'd expect Debian to have a policy of only enabling finished drivers (makes sense for a large distro) and you wouldn't enable both as that will cause conflicts. LE is happy to enable the staging driver(s) as we aren't including the vendor ones (on principle; they break often) so there is no change of conflict .. and if it happens to work that's great.