I think the range of the SEVEN (Rhodes-type range) is probably within the freq range of an 8" speaker.
Chas, the best sound I ever had for my Rhodes (back in the day) was a pair of Leslie 60 piano speakers. I added piezo tweeters to each cabinet, and it was the sweetest sound ever. It had a 10" speaker in each enclosure, and a variable true stereo tremolo. I get close to that sound today with my Korg SV-1 through a Strymon Ola dBucket chorus into my QSC 8s. Pretty damn close ... if not even better.
Are you getting used to the action on the "Sev" yet?
https://www.youtube.com/watch?v=FEZiCdYoEwY&t=424shttps://www.youtube.com/watch?v=5PQ5RPxCCOo