Get to the point will ya
Change, and 'wider wind range' is what they say to make you want a new kite. I would say different designs and brands have different characteristics. Newer big kites always seem to have 'better bottom end' Maybe, but maybe makes them slower (ss rally 14m ?). So be careful if matching kites to another size. I.e New sling RPM 12 is more powerfull than older. Have a look at Sling wind graphs over years. 2013 9m is also now more powerfull. But, is the top end less? Try is the only way to be sure. BTW a sling Rally 8m will have a bigger range and drift than an 8m RPM, so open 'c' versus delta design can be an important factor.