user85: I've looked at the way SMPPS (Shared Maximum Pay Per Share) payout schemes work, and as far as I can tell, there is no significant way to hop such a pool to advantage. Yet I've seen several people claim that SMPPS pools should not be considered hopper-proof.
Is this true even if the pool owner seeds the pool with a decent starting reserve of funds and the reserve never hits zero? Or is this only true if the pool reaches the point where it cannot make full payments to miners?
In other words, is this a realistic fear, like it is with PPS (Pay Per Share) pools? Or is this just something that comes up in a very unlikely scenario with a very unlucky pool?

user22: SMPPS and ESMPPS (Equalised SMPPS) are "hoppable" only in the sense that they don't explicitly punish hoppers. They are resilient against the prevalent style of hopping but they do nothing to lessen the gains of users who hop away. For this reason, SMPPS (and ESMPPS) are considered "fair" algorithms by hoppers and pools using E/SMPPS are often chosen as "backup pools" to be mined at when no other pools meet their specific criteria. Algorithms like PPLNS (Pay Per Last N Shares) punish anyone who isn't a 24/7 miner regardless of when or how they choose to hop in/out and so aren't even viable as backup pools.
In short, it's not realistic (to my knowledge) to say that SMPPS could be in any way gamed by pool hoppers. They are, however, fair to hoppers who choose to use them as a backup pool and so many who are staunchly anti-hopping still consider SMPPS to be bad/inadequate.

user575: SMPPS can be hopped, but not in the same way that proportional can. Proportional is hoppable because the expected reward per share is different at different times, so hoppers mine when the reward is high (early in a round) and leave when it is low.
In SMPPS, the expected reward is in theory constant, but the maturity time, the time it takes to actually receive the reward, is not (maturity time is bad because of the time value of money, uncertainty wrt the future of the pool, etc). When the buffer is positive, SMPPS is very attractive, as it is like PPS but with 0 fee. When proportional pools become extinct, hoppers will choose to mine in SMPPS when its buffer is positive because it is better than alternatives. When the buffer is negative the maturity time is high, so the hoppers will leave, and the honest miners will suffer from more than their fair share of the bad times.
So, the hoppability relies on the possibility of a negative buffer. But this possibility is very real - the underlying stochastic process is similar to the one in PPS, but the fee which helps PPS stay afloat is absent. This means that with probability 100% it will become negative at some point, no matter what the initial buffer was.
See also Analysis of Bitcoin pooled mining reward systems for more information about reward systems.

85: <p>I've looked at the way SMPPS (<a href="http://eligius.st/wiki/index.php/Shared_Maximum_PPS#Basic_Idea" rel="nofollow">Shared Maximum Pay Per Share</a>) payout schemes work, and as far as I can tell, there is no significant way to hop such a pool to advantage. Yet I've seen several people claim that SMPPS pools should not be considered hopper-proof.</p>

<p>Is this true even if the pool owner seeds the pool with a decent starting reserve of funds and the reserve never hits zero? Or is this only true if the pool reaches the point where it cannot make full payments to miners?</p>

<p>In other words, is this a realistic fear, like it is with PPS (Pay Per Share) pools? Or is this just something that comes up in a very unlikely scenario with a very unlucky pool?</p>
 22: <p>SMPPS and ESMPPS (<a href="http://eligius.st/wiki/index.php/Shared_Maximum_PPS#Equalized_SMPPS_.28ESMPPS.29" rel="nofollow">Equalised SMPPS</a>) are "hoppable" only in the sense that they don't explicitly punish hoppers. They are resilient against the prevalent style of hopping but they do nothing to lessen the gains of users who hop away. For this reason, SMPPS (and ESMPPS) are considered "fair" algorithms by hoppers and pools using E/SMPPS are often chosen as "backup pools" to be mined at when no other pools meet their specific criteria. Algorithms like PPLNS (<a href="http://eligius.st/wiki/index.php/Pay_Per_Last_N_Shares" rel="nofollow">Pay Per Last N Shares</a>) punish anyone who isn't a 24/7 miner regardless of when or how they choose to hop in/out and so aren't even viable as backup pools.</p>

<p>In short, it's not realistic (to my knowledge) to say that SMPPS could be in any way gamed by pool hoppers. They are, however, fair to hoppers who choose to use them as a backup pool and so many who are staunchly anti-hopping still consider SMPPS to be bad/inadequate.</p>
 575: <p>SMPPS can be hopped, but not in the same way that proportional can. Proportional is hoppable because the expected reward per share is different at different times, so hoppers mine when the reward is high (early in a round) and leave when it is low.</p>

<p>In SMPPS, the expected reward is in theory constant, but the maturity time, the time it takes to actually receive the reward, is not (maturity time is bad because of the time value of money, uncertainty wrt the future of the pool, etc). When the buffer is positive, SMPPS is very attractive, as it is like PPS but with 0 fee. When proportional pools become extinct, hoppers will choose to mine in SMPPS when its buffer is positive because it is better than alternatives. When the buffer is negative the maturity time is high, so the hoppers will leave, and the honest miners will suffer from more than their fair share of the bad times.</p>

<p>So, the hoppability relies on the possibility of a negative buffer. But this possibility is very real - the underlying stochastic process is similar to the one in PPS, but the fee which helps PPS stay afloat is absent. This means that with probability 100% it will become negative at some point, no matter what the initial buffer was.</p>

<p>See also <a href="https://bitcoil.co.il/pool_analysis.pdf" rel="nofollow">Analysis of Bitcoin pooled mining reward systems</a> for more information about reward systems.</p>
