LimeWire reduced the outgoing bandwidth limit for ultrapeers in a first step to 8kb/s, so upload performance should not be a major issue. - I think LimeWire could go as low as 5kb/s once traffic compression is activated by default.

As a general rule, the more ultrapeers there are, the lower the bandwidth requirement per ultrapeer.

More ultrapeer connections do not increase the number of redundant connections if you reduce the TTL at the same time. The number of redundant connection is a function of your theoretical network horizon, not of the number of ultrapeer connections.

LimeWire is not very good at keeping connections to other vendors because other vendors do not support this so-called 'high-outdegree network' yet. You can expect that to change with the next BearShare release. The new BearShare betas already connect to LimeWire very well.

And you don't really want good connections to lame GnucDNA client, - because they can mess up your searches. If you search for "the song xy" GnucDNA based clients (Morpheus, Gnucleus, Mynapster) seem return all results containing "the", "song" or "xy" - and that can really hurt you when your ultrapeers will return only so many results and all of them are completely unrelated to what you were searching for because you have a couple of GnucDNA clients in your neighbourhood.