In reply to ablackett:
Hallo
If you come across it, DOC's "you're all going to die" attitude is usual. Don't worry about it. (not sure if you're current in the zealand or not, sorry if this is all well known to you)
Milford is a pass in the middle of some nice flat valleys. I did it a few years ago in the proscribed 4 days with a big bag (including things like fresh eggs and beer - really embracing the kiwi tramping attitude), and I doubt i walked for more than about 4 hours a day. I did a lot of lounging in huts (also the kiwi way).
The boat doesn't go from Te Anau - it goes from Te Anau Downs, which is about 30 mins drive north. I worked at the hotel there at TAD for a few months a few years ago. It might have changed, but I probably wouldn't choose to stay there and there are bus transfers from TA. The boat takes an hour and a half, so it would get you to the track about midday. And if you're looking at going over christmas, I'd check out with Real Journeys how far in advance you need to book and if you can change it. I reckon it will get booked up early, which isn't so good for you if you're waiting for a nice day.
You'll have to overtake a LOT of slow groups, not just the people staying in the DOC huts (who are a range of ability), but there are guided walks going at the same time. so there's probably 200 independed walkers on the track, plus another 200 in the guided groups. Might slow you down a bit (about 90% have at least two walking poles - super trip hazard!).
Of course it's up to you, but if you're based in Te Anau and you haven't done it yet, have you considered running the Kepler Track? You might be a bit late for this:
http://www.keplerchallenge.co.nz/
Its a lovely ridge path and would be a fantastic (and round trip!) run on a clear day and there's a 4hr37min record to beat. I enjoyed it more than the milford and nothing would need to be booked, so you could do it on a nice day.
Good luck with whatever you decide - have a great time and I hope the weather smiles on you. I'd like to be down south for christmas too.
HR