May I also propose a few more suggestions, beyond the fixing / upgrading of the masternode payments system?
Of course, very interesting suggestions.
1) Block time of 1 minute could create bloat in the long run and might need upward adjustment. It is also worth looking into a mini-blockchain integration. If InstantX is also copied from Darkcoin in the future (something that only coins with masternodes can emulate - and spreadcoin will be in that position), block time can be safely revised upwards.
Don't forget that this is solo only coin. Block time should be low to allow people with less hashrate to mine.
7) CPU mining is ideal in the way it is conducted through the menu, but the mining speed should be faster / more optimized for certain architectures and instruction sets. This needs some work.
It would be ideal if GPU mining can also be integrated or "associated" from the mining menu... ie spreadcoin-qt calling the gpu miner program with the right parameters (that the newbie user doesn't know how to setup).
I spent some time optimizing integrated CPU miner before GPU miners appeared but it probably requires more work though. Note that this hashrate should be lower than in X11 by design because mining algorithm itself is slower.
10) Quantum-resistance: The ECDSA of Bitcoin / Bitcoin clones is not quantum-computing resistant. This means that once a public key is known, a private key is weaker against a QC attack.
I believe there can be two solutions for this issue: Changing the algorithms to QC-resistant and thus creating the first QC-resistant altcoin (there is the possibility that they might introduce bloat). Alternatively a work-around QC-resistance can be created through a checkbox. When ticked, all addresses with even one spend transaction will have their funds moved, automatically, to new addresses with zero spends. This will prevent the pub key from being publicly known (and thus being reversed), if and when a QC attack occurs / if and when a QC is developed and deployed. Futureproofing in this way could create a new way of crypto-diversification asset to counter a QC-attack risk (that will leave vulnerable the other coins).
I was investigating quantum-resistance some time ago. It appears that all quantum resistant digital signature algorithms have insane key and signature sizes which makes them completely impractical to store in blockchain. Your proposed future-proofing won't work, to spend any of your "secured" coins you would still need to reveal your public key.