I really wonder why redis hasn't implemented HMINCRBY. Have run into that issue a bunch of times and the Github issue just doesn't convince me.
Running MONITOR in production can severely affect performance, by 50% per monitoring client according to the documentation.<p>twemproxy independently exposes some statistics, it's probably safer to do it that way.
One common pattern I had to frequently use was HSET of the same key on multiple hashmaps and different values. Not quite HMSET, but MHSET was a good name for it.