Claude, Goldwell question

I need formula suggestions for myself.  I'm a NL 7-8 (almost 8 and no grey) that is a very, very translucent, pearly ash tone. It's very close to a Goldwell 8P, but even pearlier or similar to a Logics 7V. 

I have very, very fine hair. I love my natural color but wants some very blended, natural highlights  and lowlights (to bring me more to a level 9-10 (I love the Goldwell 10P swatch) so that I'm a shimmery silver blonde. I'm thinking alternating light/dark every other foil and gradually going light-dark-dark to keep some nice depth and dimension underneath. 

I have lowlights that are too opague and in my opinion a level too dark (Wella Color Touch 7/1-demipermanent) with Wella Color Touch 9/16 highlights (bleached with Blondor then toned demi). The highlight is okay (it's only through the crown), but the lowlight is much more concentrated (opague) than my natural color and looks too brown/gold.

I need some formula ideas for Goldwell and (maybe Logics but I don't know if you know that line).  The formula another colorist gave me was 1.5oz 8P + .5oz 6A with 10P 30vol highlights.  What do you think of this formula?  I wasn't sure that the 30vol would lift the highlight since I've already got a demi lowlight on my hair (color doesn't lift color, right?).  Also, could this be too dark since Goldwell is a European level system (starting at 2, not 1)?

My other question is will Goldwell (I've never used it but love their pearl tones) be too opaque as a lowlight?  That's my beef with Wella-it looks too heavy and dyed on my hair.  I've had Logics color in the past which are American dyes and are more translucent.  I liked the results with that but no salons in my area use it, so I'm trying to decide what to do.

Sorry for the book but I can tell from all I've researched about color that you know your color theory and I value your input.

Thanks!