I don't think the IR cut filters are generally required on R-D1 for decent colour work, but they can be very useful. The R-D1 is pretty sensitive to IR, although the difference against M8 is significant. I have both the Leica M8 and R-D1, and I actually tend to remove the filter when switching a lens from M8 to R-D1. Nevertheless, I think it is a good idea to try IR cut filters on R-D1 yourself to understand the effect they have in practice. The filters are quite pricey, so don't rush to buy a whole set based on Internet chat only.
Here's a photo using Summicron-M 50 (without filter) on R-D1 which shows the effect of the high IR sensitivity. I believe both the trousers on the woman and the man's socks were grey or black, I'm not so sure on the man's trousers. There is clearly a cast. This is an extreme example from what I have shot.