There are tons of new blocks and features to balance and a lot of suggestions about what should or shouldn't be added along with a version update. Fortunately, PizzaMC has already said in another thread "We are planning on upgrading the non pvp servers' versions soon." They're working on it.
As a side note:
Another big concern for people running multiplayer servers is lag caused by automatic farms. Tileable BUD sugarcane/melon farms using the observer block cause less than 1/8 the number of block updates, making average farms somewhat more SMP friendly.
Sugarcane example:
1.10.2 BUD =
1.11+ BUD =
http://imgur.com/jymUR8g