Bill Smythe and I have both run numerous Plus Score events, and assuming they draw enough entrants, they do well for both the player and the organizer. You can tweak the payout matrix quite a bit, so if you really think a 5.0 score is worth a lot more than a 4.5 score then you can do that.
No, they don’t offer lottery-class prizes like some organizers do. And they don’t subsidize titled players and masters, but most of those are an area code or two away from me.
You can avoid all the convoluted prize distributions in the USCF rule book by stating in all your publicity that you will NOT be following the USCF guidelines. This is perfectly legal, the USCF rule book only applies if you have not announced other rules. For example a fairly common alternate system is that everyone that scores a perfect 5 wins $xx. Everyone that scores 4.5 wins $xy, etc. As long as you announce in advance what the deal is you can do that, or, whatever you want.
For ease of calculating the distribution you might use a manually calculated “Top Down, you can win multiple prizes” system. So, starting at the top you can see that 1747 and 1591 would split the $150. Moving down to the next prize you see that the top Class B player is 1747, he/she gets the $75. Then the top Class C player is 1591, he/she wins again and would get the $75. Simple and easy to use.
And in my opinion it is more fair. 1747 did win 1st-2nd AND he/she had the best score of the Class Bs. Why not get paid for both? Likewise with 1591,1st-2nd AND best score in Class C . And why should 1910 win anything at all? 1910 wasn’t 1st or 2nd and wasn’t in a Class that had a prize, yet the USCF says to pay him/her.
The main advantage of the USCF default prize distribution is that by limiting to one prize per player you ‘share the wealth’ and, I suppose, encourage more players to continue to play tournaments.
Or make up your own system. But if you do be sure to announce it in all ads and publicity.