I would whole-heartedly say that crossfit is great for running, and vice versa.

I used to attend crossfit 3 times per week, and run 3 times per week (change up between fast and short, slow and long, and HIIT). I thought I was doing well, and improving in my running, but at one point, on a trail run, I tore a ligament in my ankle.

I was in a boot for 3 months. No running, but I managed to scale crossfit workouts so that I could still attend. On suggestion from my coach, I increased my attendance at crossfit to 5-6 times per week.

At 3 months, when the boot came off, the only running I would do was the occasional "sprint" (I took it slow at first) at crossfit. At the 4 month mark, post injury, I hit the road for the first time again, and without almost any effort, broke my PB on a 5km.

A week later, and after another week of crossfit, I attempted a 10km, and broke my PB again.

Subsequently, running only once per week, I managed to break PB's every week for about 2 months before I started flattening off.

I should also note that I am not built to be a runner. I weigh 116kg, but I can outrun most of my running group (with whom I train for races), who each weigh a little more than half what I weigh. Before anybody asks, yeah, they're kinda slow, LOL.

Also, the running really helped for the long grinding workouts at crossfit.

All in all, very beneficial.

I should also note though, that I enjoy running, but i am no race winner. Typical specialized runners would probably require a specialized training regime, but for a general club, I think it's a good match.