no, not really, - LimeWire ultrapeers for example impose a bandwidth limit of 15k/s on outgoing messaging traffic, so you won't be able to tell any difference between most ultrapeers. The rest of the ultrapeers are likely to be dropped automatically.

Over the next few months results will become better, since the major clients are going to implement upload queues and partial file sharing (in a much more sophisticated way then eDonkey does). The upload queues will probably reduce the amount of requeries sent substantially (indirectly increasing your search horizon) and the partial file sharing is going to increase the availability, especially of large files.

Sadly, we will have to wait at least three or four months until those new features will be available throught the gnutella network. It is true that Shareaza already implemented those two and Gnucleus is already testing partial file sharing, but as far as LimeWire, BearShare and Morpheus are concerned (those clients make up for the vast majority of nodes) they are not yet working on that.