user78: Some pools / payout mechanisms are vulnerable to pool hopping.
Is P2Pool vulnerable?

user323: From the Wiki on P2Pool:

Each share contains a generation transaction that pays out to the previous n shares, where n is the number of shares whose total work is equal to 3 times the average work required to solve a block, or 17280, whichever is smaller. Payouts are weighted based on the amount of work each share took to solve - proportional to the p2pool difficulty at that time. 

So it works like a PPLNS pool, which is not vulnerable to pool hopping.

78: <p>Some pools / payout mechanisms are vulnerable to <a href="https://bitcoil.co.il/pool_analysis.pdf" rel="nofollow">pool hopping</a>.</p>

<p>Is <a href="https://en.bitcoin.it/wiki/P2Pool" rel="nofollow">P2Pool</a> vulnerable?</p>
 323: <p>From the <a href="https://en.bitcoin.it/wiki/P2Pool#Payout_logic" rel="nofollow">Wiki on P2Pool</a>:</p>

<blockquote>
  <p>Each share contains a generation transaction that pays out to the previous n shares, where n is the number of shares whose total work is equal to 3 times the average work required to solve a block, or 17280, whichever is smaller. Payouts are weighted based on the amount of work each share took to solve - proportional to the p2pool difficulty at that time. </p>
</blockquote>

<p>So it works like a PPLNS pool, which is not vulnerable to pool hopping.</p>
