Just for an update, I did end up buying the 7/8 Rio Switch line. I wish I was a better caster to give perhaps a more accurate review of the line but I will say that for what I used it for (fairly short-range nymphing), it worked very well. I also had the opportunity to switch it with the 6/7 Rio Switch line one day and the peformance (again for the nymphing application) was much worse with the 6/7.

We also tried the 6/7 and the 7/8 on a nice Sage Z axis 7wt switch and all agreed the 7/8 was the right fit. The Sage with the 7/8 was a straight-up powerhouse of a setup.

Your mileage may vary.

-AP