Dear Cofty, what a great letter ! I do hope it is published !
My only observation is that your idea of including a link to a site is excellent, I would suggest only one, and that would be JW Facts, the reason being I feel that this site is easier to understand and navigate for a non-JW, and may save somebody, Freeminds is great, but more for Ex-JW's, and has a Christian agenda.
Also, one or two of your old friends from the K.H may be tempted by its name, they may think, "I'll find some errors in those "facts" " and have a look.
Perhaps a phrase to introduce the site, such as "this site is of immense help in understanding the methods and errors of this high-control group".
Very good luck !
Edited to say : I do think it would be harder hitting to say something like "their denial that Jesus is divine" or something similar, rather than Arian Controversy, and it may resonate with ordinary Christians that JW's are weird ! After all it is the virtually uneducated that JW's mainly target, so maybe after saying you were ejected for Apostasy(people may not know what it is according to JW's) perhaps add "merely disagreeing with some of their strange ideas". Just my two cents.
Again, good work, and the best of luck !