That's the beauty of Vinyl, if you don't like it you can tear it off. I personally think a white or cream roof would look so good with your car how it is at the minute, but that's just me.
I'm not sure, but I would suspect that carbon effect may me more difficult than a plain colour as when I applied heat to get the vinyl to go with the curves it distorted. I'm not sure how much distortion is involved, whether it would be noticeable. It's obviously possible as I've seen it done, but I wouldn't trust myself to do it first time.