This needs some comment on proper usage (locking, isolation, ...) of these to avoid deadlocks (one thread inserts, other updates at the same time, ...). Without this this incomplete and of limited use.
I use MSSQL on a current project and really don't like it's query optimizer. It relies too much on statistics which means that slightly complex queries get random behavior really quickly, especially in the beginning as the database if growing.
IMO, completely unsuitable for web apps where DBA is not sitting around 24/7.
Yup, it's not really specific to SSH. The same problems occur using SSL X509 client certificates. Non-technical users will get confused unless they have a smart card/token that secures their private key.
Using sane/standard logging should be the first thing an installer asks before installing systemd based OS. In fact, just make separate .isos for this.
(and I like systemd, at least in theory - and running Fedora 20).