I'd like to say, I dyed my hair recently to a reddish colour that's a bit lighter than my natural colour and what it really did was kind of throw in red with my brown so it's kind of inter-mixed (like Maria was saying about Annie). So my hair still looks brown but more like a lighter more reddish shade. It changes depending on the lighting of the room I'm in.
My roots are starting to come in now but they really aren't super noticeable just because of the colour I went with.
Also, even if you only go with highlights, if you go with something very different from your natural colour you will still eventually have to dye it again or cut it because you will still have the highlighted hair/non-highlighted hair contrast. Soo if you want to avoid that I'd suggest going with something similar. But whatever floats your boat, really. Personally I'm really happy with how my hair came out so even if I do have to dye it again to fix it I still think it's worth it just because of how much I enjoyed it the way it is now.