Important edit:
I've set up a data collection sheet that shows averages and all. You will find it here. It should be rather self explanatory. Kudos to Zeddy for helping me with the formula for calculating stuff per minute 'cause I was too tired for doing maths last night.
If you'd like to submit data, please post it here, mail me in game (IGN: Krakob), contact me on Steam or whatever. The data I'll want is run date, runner(s), run time, raw crowns, special items, and notes if you have any. If I don't really know you, I'd prefer if you were to provide as much screenshot proof as possible.
Please note that I want proper times. If your party took several minutes to speak about economical issues in Italy or someone spent 5 min AFK, I'll pass on your submission. Same goes for normal runs that include lots of unneeded combat.
You might note that I have some bad data at the moment but I'll get rid of it as soon as I get proper data.
For timing, start it when the 0% appears on the loading screen for the first stage and stop it when the screen flashes white upon defeating the boss. I recommend that you either grab something here from the timing section or use http://www.online-stopwatch.com/
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I figured this out now that O:CH is free but it has been possible since the Sprite patch. If you're like me, chances are you have an eternal supply of Eternal Orbs of Alchemy. Nothing to use them on because the choke point of crafting is the Elite Orbs and Shining Fire Crystals. But there is one 5* craft that doesn't involve any 4* item and that's the Perfect Mask of Seerus. The mask can be vendored for 30k CR, much like a piece of Ancient Plate gear.
First, let's look at pure payout in crowns. For simplicity's sake and since I haven't visited Seerus since before the Sprites, let's go with the old CR data, which is the same as for the difficulty Advanced.
Average O:CH advanced payout is I think 4.5k CR and average KoA payout is about 7.7k CR.
Vana gives 3 Almirian Seals per run, which are worth 1k CR each. Seerus gives a fragment of his mask each run, which is worth 10k if we only count the fragments in the craft. It is very notable that the craft itself costs 5k to perform, though. We also need to take two Trojan Horseshoes into account. As Sprites can feed on these and they are rather easy to get, a quick AH search leads me to believe that they are worth about 500 CR each. We can therefore conclude that a Perfect Mask of Seerus grants us a profit of 24k CR. There are other materials needed but none are 4* or higher and aren't quite worth taking into account.
24k/3=8k. Not bad for a single fragment.
To sum things up:
Average Advanced O:CH payout: 4.5k CR
Average Advanced KoA payout: 7.7k CR
Perfect Seerus Mask Fragment value: 8k CR
Almirian Seal value: 1k CR
4.5k+8k=12.5k
7.7k+3*1k=11.7k
Seerus is in the lead. Does this mean FSC farming has finally been obsoleted?!
The answer is no. Since you need Trojan Horseshoes, I reckon it'd be the best to do enough FSC to get two Trojan Horeshoes as well as to make some Eternal Orbs for every three O:CH runs you do. I don't have very exact payout data either and it should vary between difficulties. You can gain more money through speedrunning FSC on normal than doing it properly on Elite, putting more emphasis on the tokens Vana gives rather than the pure CR payout. I'm thinking the same should apply for O:CH but I've never done a speedrun of it.
If I forgot anything or if my data is incorrect, please do inform me.
Edit: the first thing I realise is that O:CH still costs some. You do get the most powerful bomb in the game and one of the coolest swords as well as the ability to craft the Perfect Mask of Seerus, though. It's roughly 1050 energy per item. I'd say it's worth it if you've got actual interest in the items available. Chaos sadly makes PMoS not so useful but it still has its uses, like SL IMF for example.
Even running OCH back when mist still existed and with an elevator pass, you could make some profit. After running tier 1 three times on the same day, crafting the Fractured Seerus Mask and then unbinding it, (100 mist, 10CE) you could sell it for something around the 20k mark. (due to it's 5-star-esque status resist, inherit abilities, accessibility, and badass appearance) You get a couple thousand crowns for the three runs, so any player could easily get some decent cash no matter their equipment or skill. Since the main focus was the material at the end, you could speed run the most of it, ignoring the stupid Mortifires.
About your math though, you're assuming that completing an OCH run takes the same amount of time as a FSC run, while killing all the enemies.