RIR SHOULD be good dual-purpose birds...same with Plymouth Rocks and many others. The problem is that these days, their egg laying ability seems to be the only trait selected for. They aren't the meaty birds that our grandparents raised.
If they are hatchery stock, don't expect a super meaty bird. If they come from someone that is trying to preserve the true dual-purpose nature of the breed...then yes, go for the RIR.
Edited to add: I've coooked up a few RIR cockerels and a Plymouth Rock cockerel. For a family of 5, it was fine for one meal...but not enough for leftovers. That's why I think it's way more bang for your buck to raise the meat birds for your meat, not hatchery quality "dual purpose" breeds.