I currently use guage 13 Martin strings on my Avalon and play a lot of lead stuff. I love the response from the heavy strings and the tone and volume is amazing. However, I heard that other manufacturers such as Martin don't recommend anything greater than medium or gauge 12 strings. I have been stringing my avalon for over two years with them and haven't noticed and problems yet. Was I lucky or will the strings cause any damage. All answers appreciated.