Well, I'm currently still on the biphasic sleep schedule. I feel ok, but I do still feel at least moderately tired most days. While I'm tired, the additional time that I have to accomplish tasks is still more beneficial to me, so I am still working to make the sleeping schedule work. I still only aim to get 4.5 hours of sleep a day, but I am still contemplating taking that up to 6 hours per day.
I ended up pushing my nap back an hour, so it is now from 9:00pm until 10:30pm. I was beginning to miss those nice evenings and between working out and eating dinner, it was feeling quite rushed. I like this a little better.
Weekends have still been a problem (if you call sleeping 6 or 7 hours a problem). I slept in until about 9:00 am on both days this past weekend, and I did feel pretty good on those days.
I'm going to keep going with the schedule, and maybe play around with it a little. I am really loving the extra time that I have, and I am still hoping that I can figure out how to feel 'great' with the amount of sleep that I'm getting. Don't know if it's possible, but I'm still willing to try and find out.