The blender approach is feasible if the node structure isn't too convoluted and complex.  The problem with combining the two separate shaders is one will displace the other.  A simple select all and cut on one shader set, load the other, then paste the original will work, but it will only appear for the material zone you are working with.  The only convenient way around this that I can think of is using BB's VSSProp.  It can distribute specific shader arrangements over select material zones with custom arrangements.