How big do I need to do?

[Musashi]

I've been thinking about pairing 2 speakers from this line with a Marantz Receiver: https://valueelectronics.com/product...usiast-series/

They'll be used for playing Rock Band 4 in a big exhibit hall containing many gaming stations. I estimate the distance from speaker to furthest audience row to be about 30 feet / 9 m.

For each step up, is it a question of maximum volume, improved clarity, or what? I intend to transport these speakers in my car frequently so I was leaning on the smaller end, but am I giving up anything notable by not springing for the 9 or 11 models?