I say give them 100% of the fees indefinitely. If they funded it then they deserve 100% of the fees indefinitely unless they decide they don't want the fees and in that case burn the fees.
Is there any rational reason why they shouldn't get 100% of the fees indefinitely if they privately funded the feature? By giving them that we could encourage new efforts to privately fund features, like the bond market or prediction markets.
I think it should be 100% on the stealth transfer fees for life. What is the argument for keeping it at 25% If they paid for it they own it entirely don't they?
The flaw in this is that it overlooks the cost to the network. Granted, that isn't much compared to the non-stealth transfer volume but it isn't zero.
For this reason I am not in favor of giving this investor 100% of the stealth transfer fees. However, I think the investor is entitled to lifetime royalties, which is some percentage of the transfer fees. This is the payoff for the risk being taken.
IMO the deal is about setting a reasonable % to cover ongoing support overhead of the feature. Perhaps that should be padded to cover unknown costs, not sure about that or how much padding is reasonable. In the end it's about dividing up the transfer fees between the investor and the network. The investor has unknowns in the rate and amount of return on their investment and the network has unknowns in support / overhead costs. It's a matter of balancing those unknowns to the satisfaction of both parties and if that's possible a deal should be established.
Hypothetically, if a lifetime % of all stealth transfers are on the table, why couldn't this be crowdfunded? Lets say for example that overhead / support will require 25% of the transfer fees. That leaves 75% to be split by all of those contributing to the crowdfund. Each contributor would receive whatever cut of that 75% based on how much they contributed. If only 1 investor contributed they would receive 75% of the transfer fees for life and 25% would be held for support costs.
If there were a way to provide equal opportunity to crowd funders, such as no one person could buy more than X% of the $45K, would enough people buy in to make this happen? I seriously doubt it, so the idea that a crowdfunding for this effort limited this way seems highly unlikely. $45K @ $0.003 is 150M BTS, if BTS were even an option to fund this work.
And yes, I forgot to mention, that as important a feature as I believe stealth is, it should not be a higher priority than making our exchange UX competitive. It should NOT divert any CNX personnel away from that effort. The OP sends a message he is willing to shift priorities, and this is exactly the kind of thing that the community is saying SHOULD NOT be done. STAY FOCUSED!