I bought the DRT kit after watching the New York Saddle hunter's excellent videos on DRT climbing. The first time I tried it I wasn't very coordinated, and it was tough. I looked like a worm on a fishing line, lol. Then I went back and tried it again and now I love it. I even made a throw ball launcher out of PVC and some fittings from Lowes that uses a bicycle pump and will make a 14 OZ ball go 50 feet.
The actual climbing is awesome. The rappel down is awesome. I have no issues with tying the Blake's Hitch. I can be 30 feet up a tree in about 2 minutes. It works great in the Cruzr XC and also works fine in the Recon without the leg loops (try this one low and slow guys).
My issue is that the trees in my area just don't want to cooperate. I have 75 feet of Samson Predator rope which will get me plenty high IF I can find a suitable branch. Unfortunately, I have a dearth of trees that have their first suitable branch at about 40 feet. I am considering buying a 100-foot rope.
I made a tool to help me when considering a tree and it has saved me a lot of headaches. One thing you can run into is the limb heigh can sometimes be just a bit too high. You look at it from the ground and say, "yeah that should work", then after several throw attempts you get the ball over the limb, pull over the climbing rope, and it is just a couple of feet too short. That is frustrating. I have a tree in my yard that is right at the "goldilocks" height to maximize the rope but still be good to tie off the knots, etc. Using this as a guide, I paced off ten paces from the tree and then held a stick out at full arm's length and put the bottom of the stick in line with the base of the tree. I then marked and cut the stick to the height of the limb the rope went over. Now I can use that stick anytime I walk up to an unknown tree. If I pace ten steps out from the tree and hold that stick at arm's length putting the bottom on the base of the tree it will tell me if the limb I am thinking about is OK or too high.
I really want this method to work for me. It is very minimalist, and I feel very safe doing it. I am connected the whole way up and down.