The concept is that you'll eventually be there... or close to RuneScape gold it and the tokens you collect will be worth the same amount as they do now. So while 17k tokens may seem like a huge amount now however, in the near future they'll become pocket change and you'd prefer an additional 2 million dollars than 17k tokens (that will otherwise be spent on Dungeoneering xp).
It's a shame that at this point your head is probably made up. I've transformed your question into a convincing essay :D (more like a debate really). It's true that the other equipment you have plays large roles, as does the method Jagex offers these bonuses. And for that reason I think this is too difficult to explain mathematically. Damage increase through prayer stacks over void... There's no reason I can't use both.
Just like I said that I'm no 120 dg. There are rewards that I would like tokens for, such as CCB Rigour, CCB, CMaul, ring upgrades... If I can't get 25k tokens/hour, at minimal, I'll probably not use them to pay for chaotics. Besides, why not get the two Rigour and CCB? If you didn't realize the difference, my question was which reward is better to have next. Even if I choose one, it doesn't mean that I won't one day get both (although I'm likely to not receive the second one until I'm already 99 range).
Your system is using CCB at frosts/slayer. Frosts is a steady 2m/hr. CCB lasts 10+ hours. So a repair time of 2 minutes is basically nothing. In most cases, you'll increase by a significant amount over the amount of cash you've lost through charges. I'm able say that my the rapier will lose 0 -1% of its task , which is a mere 20k. Absolutely nothing compared to what you could make with just one drop.
If you purchase the CCB you'll be using it to replace a RCB everywhere , but you'll not have to rigour in every place. I pray for every task. Is there any reason to not use strictness? (Actually there's a good reason: Range does not get excellent prayer bonus equipment such as Proselyte. If I want prayers, I must be compromising, e.g. Sw cape for fire cape buy osrs Ava's, Divided D-tooth for ranging amulet ...)