Is there any reason not to use these new drives for server workloads with lots of random access? The specs are quite close to the SLC X25-E in most cases, and even better at some, at a fraction of the price/GB.

I think MLC vs SLC can take a different number of writes which might be important if you are using them to store log files that are constantly overwritten.

Log files are also generally sequential access, so spinning disks work just fine (and are much cheaper) for that use case.