If you like scale, dynamics, frequency range and excitement then 7k2s are hugely better than 5k2s (I have owned both). They have all the other Meridian virtues as well of course.
I forgot to add yesterday that, in order to really show their capabilities, these speakers deserve the very best sources, otherwise they can sound flat and dull. And also attention to detail on set-up really pays dividends. I am thinking here about placement (distance from back and side walls), toe-in and even such things as driver tensioning.
More controversially, investment of time and money on infrastructure will also give a considerable lift to sound quality. Here I am referring to racks and supports for associated equipment, cables, and power conditioning. I have been surprised by how much sound quality can be elevated by these means. But it would be a pity to invest in such sophisticated speakers and then not enable them to truly sparkle.