Jon,
I have no stake in your series other than the customers and friends I have who will be running in it but I believe that your commitment to a stable rules set could be extended to controlling HP.
I do not have a lot of time to type right now so I will keep this short. I have been involved in DSR for a number of years and I believe the HP war there has been detrimental to participation in the class, in fact your series or at least FB has benefited from those who chose not to stay in what is a very expensive game. In DSR the majority of the participants want an open rules set and have let the CRB know, it will remain a class that is on the cutting edge of technology and cost.
In the case of FB, both your series and the club racers have a choice now to cap the HP at a chosen number and keep the racing close and to keep the technology creep in the engine department under some level of control.
From a spectator standpoint close racing is good racing, from a racers point of view close racing is fun racing. If everyone is with in a narrow band of HP the racing has the potential to be close.
This is only my opinion but I would not perceive IIR's as making FB a spec class.