Any drawbacks to using lvm comapared to AUFS? I'd like to switch to Debian from Ubuntu - will I notice any performance differences or other restrictions?
There is a slight performance overhead with lvm, but nothing dramatic. The other advantage of the AUFS driver is that it is more proven. If you have a way to get aufs on your system (and I believe debian does), my pragmatic ops advice would be to use that and give the other drivers some time to get hardened. Of course my advice as a maintainer is that all of them are equally awesome :)
how would you compare aufs/lvm performance vs with the upcoming btrfs support?
That is the one that I presume will have the most long term continuity because of btrfs becoming the default sooner than later (isnt it already for opensuse/fedora ?)