Thanks Solomon. The strange additions to the characters in the alphabet can be dealt with by a function called ASCII folding. In the Apache Commons library the Daitch Mokotoff function does have a substitution table to do this.

I did consider building this into the BasePhonetic class but decided against it because while researching it I found that the same character could fold to different characters depending on the language.

In addition I think ASCII folding is probably worthy of its own SQL CLR function.