I used the One Touch quite successfully, but it is fragile and will wear out. Better to make your own of a similar design (see http://www.geocities.com/hairfreethere for construction info).
It performs Galvanic electrolysis, which when done properly is definitely permanent. Using the One touch for the first two thirds and then using my home made unit, I permanently removed my “bush”, but it is slow. It’s been a few years, but I think it took me like 10 hours a week for the first three months and tapered down to less than half that for the next 3 months and then it was just an occasionally touch up for a month or two and then everything was gone for good. The key is to keep at it consistently so that you catch the hairs as they come through their cycles, otherwise you’ll never attack them at the right time and you’ll never have the entire area cleared.
Now I’m 80% through with my underarms (doing it all solo with no problem). If I kept using a One Touch I’d probably be on my fourth or fifth one by now as the wires are so thin that they break internally, the design of the stylus allows salt water to get inside and rot it out, and the needles are way too easy to bend, expensive to replace, very large diameter, and basically a pain to use compared to inexpensive professional probes.
Galvanic electrolysis is extremely successful and at the same time, painstakingly slow. Pros can do it faster with Blend machines, but you have to also consider your travel time and then you’ll have lots of short trips towards the end of the process to get the stragglers. So DIY or PRO may depend on your ability to learn the process and the distance from a qualified Pro (the first time my wife went to a “Pro”, she encountered a person that even though trained, could not do the job and left her bloody.