Just wanted to report that I used this (undocumented) feature to specify a student distribution for a random effect, and it worked well, producing a modest, but nonetheless meaningful (> SE) improvement in estimation via LOO, as compared to the standard multivariate normal distribution for a group.
More background here: https://github.com/paul-buerkner/brms/issues/231
A nice feature addition.
Please also provide the following information in addition to your question:
- Operating System: Windows 10
- brms Version: 2.3