NCrunch was developed in an environment where Resharper was used daily. As far as I know, almost everyone that uses it also uses Resharper .. and the two tools work very well together.

One thing to consider is that Resharper's background solution-wide analysis does churn up a bit of CPU - so if you have NCrunch running at full tilt while you're using this feature, you might notice some sluggishness. The default NCrunch configuration does consider this though, so unless you deliberately make NCrunch hungrier than it needs to be, this should never bother you.