I don't have much seat time in a 7' beam boat, but my 8' beam is outstanding in rough water. It is mind blowing how much 'bigger' the 24 x 8 boats feel. When you park my 24 cig next to a pantera or superboat the size is noticeable. The 24 x 7 boats are great, and I feel like they do go faster with equal power. I think I would buy the nicest boat that fits my budget vs getting hung up on the 8' vs 7'.
Why don't you keep it all in the family and get a little cig to go with it's big brother?