I tried HCRI back when I was in high school. The program did work for me and I was maintaining fluency in most of my conversations for a few months after the program. However, this did not last for me. In order to maintain fluency, you have to be willing to completely change the way you speak and practice their techniques nearly every day. For me personally, the techniques I learned in order to speak fluently took away a part of my personality. I was not able to speak naturally so eventually I stopped practicing the techniques. Also, I found that the HCRI method did not translate into high pressure situations for me. HCRI will certainly help your fluency, but maintaining will be hard. But, you definitely should try it as every stutterer is different and this may be exactly what you need. At the very least it will connect you with other people who stutter. Good luck with everything!