Yes always use it as a hot prespray, mixes instantly with just a couple of stirs.
Agitate with envirodri and rinse - great results on wool and synthetics.
Like Neil, I've tried several times with MPower, sometimes I get a result, mostly I don't - Pureclean works every time.
I only resort to Powerburst on really grotty carpets. Fortunately with my client base, they are few and far between.