When you first connect to the network - LimeWire will look for hosts to connect to - it will ask them if it can connect - if yes, it will form a connection - this is an outgoing connection.

If you have been on for a while then other clients may ask if they can connect to you. This is an incoming connection.

There's no real difference between the two types of connection - it is for information rather than anything else - as such, the difference between incoming and outgoing, by itself, should not make a difference to the quality of your searches.

The difference probably lies in your ultrapeer status. As a leaf - you will not have any incoming connections. As an ultrapeer you become a popular/desirable/necessary connection for all those leaves out there and play a more significant role with other ultrapeers.

As an ultrapeer you probably do have a better search horizon and consequently a better/faster download rate. The downside is that around 15KB of your upload and download bandwidth is given over to message routing.

You can force yourself to be a Leaf with:

Options|Speed|Disable Ultrapeer

You cannot force yourself to be an ultrapeer - although there is a reasonable chance that LimeWire will elect to be an ultrapeer if you have a reasonably large bandwidth.

Mark