You are correct about Storm. When I asked them why their rate was less than BRK's the agent did not know the answer. The question is are BRK contracts on the higher rate available for new joiners? If so which would you choose? There are tiny subtle differences in the text of the contract, but over a 800hr year the drop in pay via Storm is significant. As it is RYR who decide the rates, and not the agencies, it is a RYR salary cutting move. For employees, which you are really, it is not allowed to employee 2 people on the same contract with one having less favourable conditions than the other. The subtle differences in a Storm & BRK contract seems to get round this point.
The real interesting issue is what will happen to salaries after the whole contractor scam/sham is blown wide open. If all contractors move onto the same as RYR employees the rise in crew costs will be significant. Hang on to your straps for a rocky ride to the bottom.