I'd say by comparing my M61W to my M61 and other neutral lights, that the M61 is neither warm nor neutral.
It's warmer than the M61, but definitely cooler than any of the other handful of neutral lights I have.
The M61 looks like it has a slight blue tint, while the M61W looks closer to white. If I had to guess, I'd say the M61W was about 5000k.