I'm still playing with efficiency somewhat. My experiments thus far are really not conclusive, and I'm beginning to think maybe high efficiency is not such a terrible thing after all. But, odds remain 50/50 either way. I no longer have very strong opinions of high vs. low efficiency. Bottom line is that consistency is far more important than whatever the average efficiency number is. Getting 60% efficiency consistently? Great. 90%? Well aren't you special. Somewhere in between? No worries. As long as it's consistent. If not consistent.... try to find out why, and then fix it.