In reply to Northern Star:
I had a pair of custom made insoles (I think they were from Profeet, around 2009) that they told me to use in boots and when running in trainers. After about a year I stopped using them because:
1. They weren't designed with long-term wear in the "outdoors" in mind. There was foam on top that would absorb and hold water against the foot. Wasn't great as in cold/wet conditions and with long day/multi-day use it could easily lead to trenchfoot or other NFCIs.
2. They added a huge amount of height to the heel and changed the pronation of my foot to "correct" my running stride. Instead it led to problems with knees which went away shortly after ditching them and working to reduce my heel strike.
I'm not happy with the stock insoles supplied with most boots. It staggers me that such expensive and technical items of footwear have plain-old insoles included. However, my experience with the Profeet insoles was so poor I haven't dared try something else yet.