Dr. Martens (leather boots) for tramping?

Hi, I'm planning to do quite a lot tramping around the South Island early next year sometime. Not sure exactly what tracks at the moment, but probably a good 6 weeks of tramping in total. I am currently in the process of buying/replacing gear, and it is now time to look at boots... Currently I have a pair of Dr. Martens (standard issue, somewhat like these, except not nearly as shiny http://www.freshlysocial.com/wp-content/uploads/2010/06/Dr-Martens-black1.jpg). After my old synthetic boots fell apart, I got a pair of these, just as a temporary solution. I've had them for about a year now, and have done quite a lot of day walks with these boots and a couple of over night tramps, and have found them to perform very well. I'm not sure how well they would do on longer tramps however, so I came up with a few pros/cons. Pros: Very VERY comfortable (and some say comfort comes before anything else in a tramping boot). Nicely broken in, and moulded to they shape of my feet and walking style by now too. The Air-Walk soles are great, and literally bounce you up after each step. Simple design... I'm thinking, and have experienced, that less stitching/unnecessary parts = less that can break. Pros AND Cons: Relatively heavy... Although personally I prefer a heavier boot, and have never liked ultra-light boots. Made from leather and not completely water tight (but what is?). Probably not ideal for river crossings or deep mud, but I usually like to carry a light pair of sandals or trainers for river crossings anyway. Cons: Not specifically designed for tramping or hiking. Not very much padding, although even in long uphill day hikes, over rough terrain, I haven't found this to be a problem. The soles aren't super grippy. Like I said, I've been very impressed with their durability/comfort/support/etc for short tramps, but I wonder how they would perform for longer outings (ie, 5 or 6 days at a time). I'd love to hear your opinions, cheers!