I have a similar problem and I guess I've sort of been in denial about it. I also have a difference of about an inch, but it's not due to injury per se. I've had arthritis since about 6 years of age (now 67) and one ankle has been wearing itself out over the years. For me the progression has been slow enough that I automatically compensate without thinking about it. I don't really notice it unless I'm walking or riding a fair distance. It manifests itself as lower back pain, but as mentioned above, that's from twisting the spine to compensate. However, for me a cleat block would kill the walkability of the BeBop pedals and mountain bike shoes, so that's my dilemma...