Many HHers rate the 6000's almost as highly as the 7200's. To get in your words 'a dramatic sonic improvement' I think you may need a bigger step than 7200's/5200hc. For movies, I would investigate room placement and treatment and keeping the 6000's but upgrading the 5000hc to a 7200hc. You don't say if your 6000's are 96/24 or not which may affect answers.

Meridian owner since 1992
Prime & PSU, Focal Elear headphones, Roon (ROCK 8Gi5 NUC), Explorer 1 & 2, F80. 200/203, various Sonos (via Roon).