No, performance and power consumption should go hand in hand in this case. If you are strongly IO bound, paying for the synchronization is not really going to matter much I believe.
There are cases where you can be CPU bound and using the share nothing model would work out to your advantage. There's also the case where you only have one cpu core anyway (for example if you want to get all the juice out of a cheap single core VPS)
There are cases where you can be CPU bound and using the share nothing model would work out to your advantage. There's also the case where you only have one cpu core anyway (for example if you want to get all the juice out of a cheap single core VPS)