I took a shot at cobbling together race rules for my BFRPG Dying Earth campaign by hacking apart AH's Circus Maximus chariot game and today they were put to use.
All four entries forgo attacks on each other and blazed down the track, speeding through the turn and burned it to the finish. Imagine that, the PCs long shot (actually one of the PCs was the long shot) came in first for the win!
At the same time this was going on the rest of the PCs were in the city getting ready to go with their heist they joined at the last minute. Split party doing major game stuff at the same time. I've gotten at ease with running a split party over time and I think it is an exciting dynamic when it emerges out of play. Yes it is more "efficient" to have the party together to maximize some PC to Play ratio, buut there is fun to be had switching from scene to scene at cliffhanger moments.
As far as the race rules they did an admiral job. I need to edit them for a set of rules which don't contradict themselves or make illogical play mechanics, but the concept and ease of use did come through to me. I think I'm on the right track.
And a good concept trumps all I think. This race track episode showed that yes you need rules which work, but having a straight play-balanced tactical challenge isn't necessary for a role-playing game. Good guidelines and like a race, just move it along fast. Same with the heist. Every good heist flick has the "unforeseen complications" which spring up mid-operation. Just like the race, keep the action going. PCs shouldn't have time to debate the next move. Guards are coming, goods aren't were they where supposed to be, someone arriving who should have been long gone. Change the weather, make someone go missing and not show. Pile on the complications until it turns into a flight through the city doing your best to recreate that scene from Heat but with daggers and arrows.
The brief street scenes did give some brief moments for the PCs to catch their breath and figure out how to make all the chaos pay. I don't think I'm going to give them a breather :)
Then this blog post by Aos is worth a read. It is worth a read because a) he is doing or has done what he is talking about. b) How to prepare for the necessary and expensive use of quality art, also his use of the word an analogies of commitment ring true to me, c) the Work Flow piece is really strong. I took notice of his mention to not go back and rewrite drafts. I find I do this and I'm glad to hear a fellow creator thinks "You need to write your first draft from end to end without going back and revising. It doesn’t matter if it’s garbage. It is a natural resource. Think of your first draft as mining the ore. Subsequent drafts draw out the METAL!" 
