I like the concept. I'll also say I think 5% is too low but I don't agree with those suggesting 15%+. I would like to see it closer to 10%.
Ideally the way I'd like to see this is that 100% of the SPS is burned for DEC and there's a 10% fee assessed. But they could have the option to get credits instead and only pay a 5% fee since credit can only be spent in game.
There's just something interesting about the idea of a coin that when people want to panic sell, they literally have to burn it instead.