I have also added more to the thread on the forum discussing merged mining. I have made a proposal not to merge with Bitcoin but instead of start a new purpose built currency called tokencoin that will be merged mined with Devcoin.
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Once merged mining is well tested by someone else and devcoin is well tested, an attempt will be made to add merged mining to devcoin. If successfull, the client and daemon would be changed so that in several months, long enough for almost everyone to have updated the devcoin client and daemon, the mining share would be lowered and the developer share increased. The only reason the developer share was not initially set to something really high like 95%+, was because of the risk of double spending due to low difficulty.
All merged mining does is increase the difficulty to increase the resistance to double spending attacks. It does not make one coin like another, if devcoin uses bitcoin for merged mining devcoin does not become an extractive currency, if devcoin uses namecoin for merged mining devcoin does not become a domain name currency.
The tokencoin rules would be different to the Devcoin rules. For example 100% of tokencoins would be donated to open source projects but the miner would have a few choices. The default choice would be to let them be allocated according to the receiver csv files just like the Devcoin levy but if the miner wants to chose what projects these go to they can. For instance if he/she really wants to support the reprap hacker lab in his/her city he/she could allocate x percent to that project.
When planning devcoin I considered giving miners the option of which project they want to send the open source share to. The problem is that an attacker could make an open source project that would barely qualify for devcoins. Then they would rent hash power and direct their entire share to their own project. Since they would be getting 100% of the generation and honest miners would be getting 10% of the generation, the attacker would make far more profit per hash and would therefore be stealing from the rest of the miners. Because of the enormous incentive they would get to mine, they would mine an increasing amount, eventually selling so many devcoins the price would decrease and eventually go to zero.
That's why every miner is forced to give their share to the same receivers as everyone else.
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The changes I have made are to the share line in main.cpp
static const int64 share = initialSubsidy * 1 / 10;
Devcoin is enforced sharing, a minimum of 90% of each block must be shared with the correct receivers or it is rejected. That is the point of devcoin.
Devcoin is not a charity currency where miners are asked to donate; all miners must donate at least 90% of the blocks to the receivers on the list. Miners could choose to donate more if they wanted to, but there is no reason for them to do this and they do not get anything more by donating more.