Anyone color their own hair with non-drug store br

My colorist very nicely offered to suggest a color I could use on my roots in between colorings. Then she said she wasn't familiar with drug store brands, but she recommends a semi permanent level 6 or 7 warm. Since the drug store brands don't work that way, I wound up getting Wella Color Charm demi permanent at Ricky's in what I thought was exactly what she said--the "warm" surprised me, since my hair color is a reddish brown. I would have figured it'd be "red." Anyway, my roots came out fine, but more like my root color with grey coverage than a match to the rest of my hair (I really had to do it to cover the greys anyway).

Then I read a thread on a different forum talking all about how easy it is to dye your own hair with the Wella products and how great it comes out, and I was inspired. But what I'm wondering is, if my colorist recommended level 6 or 7 in semi permanent, is that what I should be looking for in permanent as well? It seems lighter than my hair color, but I also heard that women should always pick one color lighter since they always think their hair is darker than it is. I just don't want to wind up with too light hair if I use that color level!