Would I have a red iMac on my desk, absolutely! I had a fire engine red Jeep, so the garish color works for me. Both for the color and the cause, but only if I needed a new iMac, would I make this choice. So the Red branding does little if I do not need a product, or if it isn't the exact product that I want.
Here's the deal with specially branded devices designed to support NPOs and NGOs. The idea is that some people will buy it to show their support. Others will buy it because it is different, regardless of the cause. If you don't want to show your support by having a Red product, but still want to donate to the cause, then nothing is stopping you.
For me, I'd rather donate directly, especially if there is a matching program, rather than buy something that gives a percentage.
Each year on Earth day, I visit the NPOs that I support and drop of what cash I have saved for donations, and make t-shirt purchases. Buying a supportive T-shirt is the same as purchasing a branded product like Red, so technically the NPO gets less money, but I was going to buy a t-**** anyway. I would rather x charity receive profits, instead of some commercial company.
My donations count most when there is a matching donation, like for every dollar I donate, somebody else donates the same or greater amount. I donate to NPR when I hear that somebody is offering to match donations.
I don't expect Apple to team up with Red, mostly because it is an unsubstantiated rumor.