I replace the rearmost subframe bushings on 9-5's regularly (maybe 3 sets a month) and I can tell that you don't like them
I love them! and you will love me after I share this with you...
I lower the subframe a bit by half removing the front subframe bolts and completely removing the rear. I use an air hammer with a sharp chisel to remove and an appropriately sized socket and large air hammer punch to install. Using this method I remove and replace both in about 20 minutes total. I keep the stock of bushings in the freezer (also do the rear outboard control arm bushings this way too)
Much vibration with the powerflexs? The cars I deal with are all stock power levels.