Almost all AVR's lie about RMS power. They show 100w, but that is 2ch mode, in all ch mode, they put out 60w or less. If you have ever opened up an AVR compared to a 2ch integrated, it's amazing how much stuff is packed into the AVR.
Yes, dollar for dollar you should notice an upgrade with separates. The big downfall of separates are all the cords. With an HT setup, you are talking about a dozen RCA cables, a dozen speaker cables, then all the power cables.
Have an TOTL Marantz AVR running 9.4.2, it's amazing for what it is, if the music is Atmos encoded it's cool, but my 2ch (separates) sounds so much better.