The items you mention above are all recommendations for scaling ActiveMQ as listed in the How do I configure 10s of 1000s of Queues in a single broker? page. I've utilized each of these tactics in various situations at customer sites and found that they help considerably.
The NIO transport is good for using less sockets when there are a high number of connections into a broker vs. the TCP transport. This efficiency can improve the overall performance of the broker.
I almost always recommend setting org.apache.activemq.UseDedicatedTaskRunner=false
simply because it helps considerably with performance.
Disabling tight encoding is a subtle change and difficult to see the benefit. It depends on the types of messages that you're sending.
The KahaDB outperforms any of the other stores for persistent messaging with ActiveMQ, especially on the trunk. There is a bug that is fixed only on the trunk currently that causes a dramatic increase in persistent messaging performance that will be part of 5.3.1 and 5.4.
I know that this info isn't concrete, but I hope it still helps.
Bruce