Yep, buy as big as you can for a Red. The only kits out there that go against that philosophy are Heron Bay kits, and you'll be very hard pressed to find those in the USA. Heron Bay 8L kits are comparitive to 15L or more kits. I'd say if you going to do a red kit, go for at least 16L of concentrate and juice, or choose a MM all juice or better kit.
The other reds are thin, astringent, and to my tastes are just not worth the time. Sometimes I make a 10L red kit just to use as a topper, or for Sangria or Gluwein (sometimes called Gloog in Swedish) at Christmas time.