Either one is a really nice airplane. Go look at both.
I fly a -4 and I'm building a -7. The tip up canopy and visibility on the -7, seating, and baggage volume for bigger items are what tipped the balance vs the -8. I really like my -4 so it was a tough call.
The -8 made some design choices I personally don't like of but others probably love. The sliding canopy needs a forward support and roll bar. I like the unrestricted visibility a tip-over gives. The gear towers reduce leg room and I prefer the look of the rod gear. Plus, if you have a centerline seating RV, it should have cheek cowls

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Any tandem airplane will have really big shifts in CG and differences in handling qualities with a passenger vs. solo. The builder has a choice on how to bias that.