Combination ia is obviously the fastes on this study, and even if I'd use mainly "normal" fingering im, there are passages where 1. and 3. strings are playing and on those occasions ia should be used. With ia it was much more difficult with apoyando, but with im apoyando worked fine - only the tempo wasn't quite as fast. About my guitar: it's s copy of Lacote (Paris-based builder). Fernando Sor, too, played Lacote - I think he also had guitars from other luthiers. The 7. string is handy on all 19. century music - not least with Mertz. My guitar comes from Gary Southwell (no 55, 1988), and I bought it from my friend who is a guitar builder and he is now using only his own guitars. Thanks for asking and your support, KeMe.