Sell an additional 1,000,000 MRO at 90% of the 20 day moving average of prices .. All proceeds go to dev fund ..
I will consider this sarcasm, because you can't possibly be suggesting an impromptu premine.
Some form of compulsory "tax" may be necessary for Monero, but it has to be as fairly distributed as possible.
Any compulsory tax erodes community trust, because it is still essentially a pre/post/fiatmine.
...some sort of "post-mine", e.g. every 500 blocks there is a magic block which mines an extra 500XMR straight to the dev fund
The emission curve must not change under any circumstances (except for long term behaviour). Remember how tense was the proposal to flatten the emission curve back in the beginning. I supported the change but ultimately it felt through. The opposite move will be viewed from outside as greedy and scammy even if I, you, or any of the old monerists feel it is fair.
Adding a 1% dev tax to mined blocks will not be popular, for a start if the miners are running at a 5% profit margin then that is reduced by 20%, and they will ask what are the traders and investors being made to donate?
Generally I agree with the miner tax as long as miners vote to soft-fork to the tax code. There could be some interplay with the pools also donating to the same fund - people could feel "double-taxed".
I believe the best option is to piggyback on the transaction fees. For instance, since the transaction fee hike after the spam attack, miners have seen a small increase in margins that retracted somewhat as more miners joined and drove the difficulty up. So no matter how the fees are reduced it will drive miners out. But suppose that the fees will be 0.02-0.2 XMR instead of 0.01-0.1 XMR and the fee was split equally between the miners and the devs. The transaction fee is not part of the social contract; the miners are in the same situation as if the fee was halved and the devs were getting nothing (except a slight decrease in transaction count - but since the change from 0.005 to 0.1 reduced transactions by ~25% that will not be significant); furthermore, the fees are small compared to the coinbase - XMR is still in the same regime as BTC.
I could further argue that there is consensus about the fee escalation tragedy of the commons in this thread and that is the main reason why Monero will have a perpetual debasement. If fees are to be kept NOT an incentive for the miners generally then their main purpose is spam protection. I used to think transaction fees should eventually be replaced with proof-of-work -- instead, they could entirely go to the dev team, with or without proof-of-work.
Please critique.