Aesthetix Io-Reliability Problems???

I have heard recently from several sources that the Aesthetix Io phono stage has reliability problems and that it runs through tubes very quickly. What has been the experience of Aesthetix Io owners? What types of failures have occured? Are there any non-owners who know the details of the problems? Since I am interested in the Aesthetix Callisto linestage, which is much simpler and carries fewer tubes, I would like to know if the problems with the Io extend to the Callisto as well. Thanks in advance very much for your help.