As a sometime MARRS competitor, I'll spin Mike Maqueen's comments slightly differently. I'll agree that there are in fact a few strong pockets of regional Prod competition in the US. For the last few years MARRS has seen HP (to use the class that Mike and I run) fields bigger than the vast majority of Nationals, with good levels of competition. Off the top of my head I think maybe different 5 cars sometimes running within say 3% of the HP lap record - that would be decent for a National I'd say.
Based on that alone, I'd say that MARRS could feed a good number of HP cars into the runoffs field that wouldn't embarrass themselves too much or pose a hazard to others. In fact, if you took the top half of the MARRS HP field (to use an arbitrary cutoff) you'd be applying a more stringent test than "started 4 Nationals" or whatever the Runoffs qualification has been lately.
(None of this is to say that Regionals are better, or that National efforts are not on average superior to Regional efforts)
The writing has been on the wall for a while - the first thing I thought when I heard of a Rational was "there goes the Regional / National split". It's one thing - and perfectly OK - to have a Varsity and a JV team. But when they play on the same field in the same game, it isn't Varsity and JV any more.
Seems to me that Nationals - like it or not - are going away. Being replaced by fewer "Super Nationals" (Majors) and (hopefully) a stronger Regional program. In that scenario, it would seem to make sense to feed the Runoffs from both sides.... One would hope that the Super Nationals (that has a better ring to me than Majors) would be attractive enough to stand on their own and not just as check boxes to meet Runoffs quals..
Speaking only for myself, I'd like to do the Runoffs a few times. Probably as field filler at first, but given my competitive streak I could possibly get serious later....
And honestly, as a father and a small business owner, I'm a lot more likely to do the Runoffs if I don't have to drag my car all over the eastern half of the US for half a year in addition to disappearing for a week for the Runoffs. So I can honestly say that a Regional path would be more likely to attract me.