I'm also on the prowl for my next 6wt intermediate. Are you saying you're happy with the WF6I Frequency on your 6wt rod, but are thinking a WF7I would be even better? That's sort of what I'm thinking since the Frequency is a true weight line.
Both my 6wt rods are sticks so respond well to half weight heavy or more lines. I probably should just get the Titan, but I've read good things about the Frequency intermediate. I will go with the 7 if I go that route.
My old cheap Airflo Velocity has lasted WAY longer than I could have ever imagined, but it's time to upgrade. Airflo makes them to last, that's for sure.
I love my WF4F Frequency Boost line. I wish they made a full intermediate in the Boost. It's a half heavy line, made for beginners, and casts very well shooting or on long lines. It's like if the Titan had more manners.