If you friend is trully just that he/she would..........oops sorry wrong list.
Is this just not simply the magic chain deflection / way too many gears on the back problem made popular by big S and only slightly less of a problem by "shadow-of-it's-former-self" small open-C ? I've found this chain rub appears worse on "new" 105 and less on Ultegra (Classic content is the groupset formerly known as 600) and almost non-existent on D*r! A@e. when running small front / second small rear. I (guess) it's got a lot to do with them designing the whole drivetrain for a specific length (no less than 405 mm) from the BB c.l. to rear axle c.l. and reducing the spacing between the chainrings to acomodate the 9 narrow and 10 ridiculous chains - but then again what do I know.
Classic Content (honest Dale - yes I should know better, Chuck)
Am I the only one that get's SRAM/Sachs "modern" chains to skip over the top of the rear sprockets of classic freewheels (America by Regina) and ride along the tops without actually engaging the teeth in chain ?