The pool I ran for bitcoins averaged ~110-115% efficiency, but that was on a dedicated server (not a VPS) in Germany with 1gbit/1gbit switch (200mbps guaranteed but in practice could 99% of the time get 80MB/s + ).  Averaged around 3-5% DOA for me and about 2-4% orphans.

When I initially tried to set up my home connection, I was getting around 0-1% DOA and 15-20% orphans.  A few percentage of the orphan rate was from being in the US instead of France/Germany/Netherlands where most of these dedicated servers & VPS are running.  Most was from my 768kbps upstream cap.

Later on I was able to set it up w/ 0-1% DOA and an orphan rate under 10% (though it still wasn't as good as just using German remote server, after share time got changed to 30s)... anyway, the deal is, just have bitcoind connect to 1 or 2 servers & also your p2pool node need only connect to a handful of servers...  you just have to pick the right ones.  I have no clue what those are anymore.  (ie, change outgoing connections to 0 and handpick the servers to connect to)

ed: i think you can find a VPS for a couple of bucks to run a bitcoind relay on