I'm not sure how familiar you are with the pencil mod but you can mod these in either direction, undervolt or overvolt.  The idea of undervolting (what i've done) is to lower you hashing power and your power consumption at the same time.  The way the S1's work as you lower both the power consumption lowers faster than your hashing power so you can increase your hash per watt.  So far everything is working fine.  What you loose is overall hashing power, you gain in efficiency.  I think I might actually be throwing less errors (as a percentage of hash) than I did before the mod.  Either way I've always had a really low amount of errors.

The nice thing abotu the pencil mod is that its really easy to un-do so when (not if) the price of BTCs goes back up sufficiently high enough I can un-do the pencil mod and overclock these back up for full raw hashing power.

 Let me know if this answers your question or if you're interested in hearing more.