Shapovalov has been working on Reiser4 support for TRIM/Discard on SSDs. It's been some weeks since the last revision but the fourth version of the patches are now out there for this common file-system feature of being able to discard blocks by informing the solid-state drive about blocks that are no longer in use by the file-system. Most mainline Linux file-systems already support SSD discard, which is generally exposed via the discard mount option -- which is also the case for Reiser4.
The new Reiser4 discard patches can be found on the ReiserFS mailing list and hopefully will make it into the next Reiser4 file-system revision when the out-of-tree code is update for the Linux 3.15/3.16 kernel compatibility.
My most recent Reiser4 Linux benchmarks are from last summer so within the next major kernel revision or two I'll try to get out a fresh file-system comparison incorporating ZFS, Reiser4, and the usual mainline candidates we frequently cover on Phoronix.