The main issue with the Evo IV is that the chassis is too stiff and it does tweak quite easily. The 415 has more flex in it to get the extra traction needed. This is straight from the mouths of, Surikarn, Rheinard, and other Japanese TRF guys. They all would rather run the 415 in Modified.
But..... if you intend on running Stock or 19T, then the Evo IV is an awesome chassis, because the flex issue isn't really required and also the drivetrain is UBER efficient. I'd also probably think that the Evo IV would be good in Modified Foam racing, but I haven't really tested that theory because we race rubbers here.