I have a pair of DC 13.4 with the Headsets Inc Mod. The actual ANR side of this mod is very good. Only a few weeks I ago I tried them versus the DC X11 and the Bose headsets. Personally I wouldn't splash out the money for the X11s as I thought mine were at least equivalent to them. The bose's on the other hand were better and if mine break again I would consider upgrading. Anyway back to the topic. The headsets inc mod is very good but it does have its limitations they are:
1. I have been through 2 cords that run from the headset to the battery box. This I believe, and I suspect they know, is a VERY weak point of the whole design. Where the cord meets the battery box is very flimsy and breaks very easily - so If you do buy it you need to be very careful because if you knew how tinky it was under that plastic cap with heatshrink for padding you would be very surprised. Unfortunately my second cord started playing up after only a few months
2. They tend to be a little thirsty on batteries. They use a 9V. I buy duracell 9V's and I get about month out of them - approx 45 hours. The Bose's I hear get atleast that on rechargeables! Rechargeables obviously dont last that long...maybe 2 weeks but probably more like 9-10 days.
Overall though they are a great solution without having to fork out a $1000 or more. I would take them over a set of DC 13.4 without them anyday of the week, they just have a couple of limitations that if you are aware of...might make them last a little longer. So if you are definately not in the market for a set of Bose's and just want to protect your hearing...definately go for it...you wont regret it.