When you lose your UltraPeer connection, you should be automatically reconnected to the network. You are permanently disconnected when you lose the UltraPeer? Can you repeat this? I would also recommend using the LimeWire 1.9c beta, released yesterday.

As far as the N-tier network goes, this is in effect what UltraPeers do, as the UltraPeers only allow as many new connection as they handle.

We are aware of the issue with getting fewer results. This should change pretty quickly when the UltraPeer implementation becomes the final release version, as this will effectively increase the number of hosts reached with each search.