Rabbit Pass route - Wilkin & E. Matukituki Valleys

I'm planning on doing this route some time around December 2008/January 2009 and looking for more detailed information. I'm reasonably exprerienced, a lot of bushwalking in Australia, couple of trips to Nepal and this will be my 6th tramping trip to NZ. There will be 2 of us for this self organised Rabbit Pass trip, both about the same level of experience. The only part of the route I'm not quite sure about is the Waterfall Face as there is not a lot of information other then "it is tricky" or "it can be dangerous" etc. Probably the best way for me to get an idea of what it is actually like is if I can get some comparisons with other tramps I have done. How does the Waterfall Face route compare with say the Cascade Saddle Route in terms of degree of difficulty. Would it be advisable to carry a rope, I've heard the descent from Rabbit Pass into E. Matukituki can be a little difficult also (we have no climbing experience). Have done the Cascade Saddle route (from W. Matukituki to Dart Valley) in early April (camped on the saddle), very little snow/ice around at that time of year. Is there likely to be snow/ice on Rabbit Pass/Waterfall face around December/January. We always build spare days into our trips in case of bad weather and we take our time to enjoy the experience. Will probably take 6 days from Top Forks Hut to Raspberry Creek (incl. day trip to Lake Dianna etc.) and we intend camping at the bottom of Waterfall Face and again on top of Rabbit Pass, so we can have a good look around. We would also carry an EPIRB for this trip. I've done quite a bit of googling and found some info on the rout but if anyone could also point me at more detailed info, it would be much appreciated.