Ok, Here`s my take on things (outsider`s perspective) :
I always wanted to do the Worrell 1000, ever since I heard of it. It`s not likely to happen, but if I lived in the US it would have been on my 'must-do-before-I-die' list.
Without the OBX 500, the Tybee 500 looks like half the challenge, although that is no fault of the organisers, but of a lack of participation in the 2nd leg, probably budget & time constraints due to the fact that most people who earn enough to do the event struggle to get much free time from work, especially if self-employed. Unfortunately, I think that the full 1000mile race would attract more wanna-be participants than actual entries, but would elevate the event back to what it once was, at least in the eyes of the spectators/fans.
That being said, if I lived in the US, I`d drive 4 days across country towing my boat and use up all my annual leave to do so, but don`t think I`d buy a boat just to do the event. Some (like Mike Hill) have done so, but I see that as narrowing down the possible list of would-be-competitors.
I would participate in an event of this nature, not to win it or even try, but just to have taken part and hopefully completed it. If I owned an F18, I`d want to do it on that, If I owned an F16, likewise. If there were enough boats in my class, well then I could try & win first in class, not overall.
I know many will say that an F16/F18 is not up to the task, for sure it won`t be the fastest and you won`t win outright, but if these boats are what you are most comfortable sailing in rough conditions, then you are safer than if you bought an I-20 and are too light to handle it. Even less safe is if you chartered a boat and have never sailed it before the event.
This might open the event up to more aspirant long-distance sailors, if they could sail what they want to and feel safest on. Perhaps have an F20, F18 and F16 class, if I arrived and was the only F16 I`d still participate, just for the challenge. If F20 consists of all I-20`s and one N6.0 or M20, it will all sort itself out.
Perhaps look at some sort of criteria, like a min. & max. projected performance based on ISAF rating, so no boat rated faster than 0.94, or slower than 1.04, could enter. This would create a theoretical performance separation of about 10%, or 48min in 8hours of racing. (reality is, of course, not strongly based on statistics, and you might get a surprise either way.)
You might see a few UK sailors who sail Spitfires or Stealths taking an interest, perhaps a few FX-1 sailors (double-handed) and a couple of Hobie 21`s. Eric might bring his ARC-21 if it rated within the parameters.
Macca might bring a T5.7 on steroids.
If opening up the event to attract more participants would be a bad thing for the event, then I`m missing something.
And for goodness sake, let the Tornado`s come & play if they want to, the top I-20 sailors will still have a good shot at winning, looking at the ratings (0.94 vs 0.95).
Half of what`s wrong in our sport is segregation - "we`ve organised a fantastic event, but only for one class of boat". Look, I get the OD principle, it`s the sailor not the boat etc, but I think that it keeps the fleet small and the interest from outside low.

Just my opinion of course - no I-20 sailors were harmed in the writing of this post .

Steve