Like I mentioned before, in Marc Merlin talk at LCA2015, is specifically recommends against using kernels 3.15 to 3.16.1 - Debian Jessie has 3.16.0...
I personally would be nervous about going against Marc's recommendations here.
Unless of course the Debian kernel has fixes back ported.
I enabled quota's on the default Jessie kernel and it all blew up, so at least that is broken. Disabling quotas was sufficient to put it right again. Running low on space (>10%) also really hurt performance badly (my limited experience with zfs is that it hangs badly when free space gets under about 20%). I upgraded to 4.x at about the same time as I resolved the disk space problem so I can't say if 4.x improves the low-space performance issues though. The problem I had is that I had mythtv storage in a subvolume, and the only control you have over mythtv is that you can tell it to leave a certain amount of GB free, and the maximum that can be is 200GB, so obviously that's a problem on all but the smallest installations. I ended up creating a 1TB file (with nocow enabled) and used ext4 on loopback as my mythtv store. Performance is probably badly impacted but I don't notice it. James