It does sound a bit OTT if you ask me, I usually just use a SBR scratch with some of the water proofer that sovereign recommends then render lite to help with insulating the wall.
I also make sure to check the ground conditions/drainage around the house.
Many a time I have found that ground water is the problem more than DPC failure.
Most remedial suppliers tend to specify heavy on the product for a reason, after all they need the Christmas bonuses lol