Bit of an older thread but I thought I would just add some info here for anyone preparing like I am (going in April 2014). Basically I would favor the Glasgow Track over the Warburton-Mt DB trail, the reasons are below. I should mention here for some context that I am young and already quite fit and healthy, am carrying my own pack (about 15kg load) and haven't really done hiking like this before.

I initially tried the Warburton to Mt Donna Buang trail given it was the longest and highest. I found the track very steep and tough (a good thing) with barely any flat, however only for the first half. The first half is also very narrow and overgrown (the part at the very start near the farm has lots of prickles especially), and in several places you have to climb over, around or under fallen trees. From Warburton, once you hit Mt Donna Buang Rd it gets pretty darn easy from there and I didn't think the extra 3km or whatever it is to the summit was worth it for training purposes. Do it once I would say as the view is quite nice, however you won't get anything physically out of it, at least I didn't. Took me about 2 hours to get to the summit from the bottom, that was with having the occasional minute or two break on the way up.

Next I tried the Glasgow track. I found it quite short (only 1km and took me 38mins to get to the top), very steep, rough and rocky. Again I thought the roughness is good, and it was definitely more rough than the Warburton track. The things i liked most was you really had to think about footing, the track was busy with people but not too crowded and wide enough to accommodate all, and is closer to town.

The Warburton track is a bit too far away and more remote. I didn't see one person on the track and because of its length it's a long way back to the car or the road if something goes wrong (I was worried about snakes too). Warburton is also more of a commitment due to its length, where as Glasgow you could pop in for one quick hill session. I think that doing two Glasgows would be about equal to the first half of the Warburton track, and from what I hear (I haven't done Kokoda yet) about four Glasgow ascents is about equal to one day on Kokoda.

I'll be hitting up the Glasgow track from now on as it's closer to home and I feel a bit safer there when going on my own. It's just as physically demanding depending on how many you do or hard you go. I plan to get to a point where I can do four Glasgows a day over successive days, with more weight than I'll carry and without pulling up too sore the next day.