Can an SMPPS (Shared Maximum Pay Per Share) pool be hopped? 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?
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.