I have really dark brown hair as well, and have had it various shades of red throughout the years. I love reds! Just too bad they are such a hassle to maintain, and almost impossible to dye over if you want to return to your natural colour. I had red in the bottom of my hair for a couple of years after dying long hair brilliant red with black streaks back in the 80's. It is only recently I have moved into the rich dark chocolate shades and have moved away from the reds.
Any time I have gone lighter, it has always involved peroxide. When I had bright copper all throughout or chunking in it, the hair had to be totally bleached out first, then the red put in afterward. I have used temp colours, at home and at the hair stylists, in reddish shades and find the colour doesn't last long. Permanent is much better. Actually, red is the fastest fading colour you can get. A few things I have found that help with keeping red shades looking lively are: not shampooing unless totally necessary, I used to do a lot of conditioner washes and found that Suave Naturals makes a great conditioner wash; using only a real mild shampoo, preferably one without sodium laureth sulfate or sodium lauryl sulfate as both are rather stripping to hair, Scruples Moisture Bath is good for coloured hair; use a hair wash that deposits red tones back on the hair shaft - I used to use one of these years ago and you have to be careful it doesn't leave a red ring on the side of the tub
Good luck, and enjoy your new colour! Red can be a real hassle at times and can be expensive to upkeep, but well worth it.
I just had another thought... What about just having some bright copper streaks put in? I have had small and large strips put in underneath the canopy so they just peak out. That way, the roots don't show and you don't end up damaging all your hair. You could always have them put in the same way as blond streaks are put in, and keep the rest of your hair natural else dye it a darker shade. I had a friend who used to get her hair dyed almost black with bright red streaks down the front, and it always looked spectacular on her. Sometimes, she would have two or three different shades of red around the front of her hair. The same hair dresser used to do mine in a diamond formation on the top keeping it real dark, with the middle the light shade of red, and the underside really dark again. It was almost like sandwiching the brighter colour with dark, and made for an interesting colour effect.
Anyhow...Have fun with whatever you decide to do! You can always recolour or cut it into a cute short style if you don't like it.