In that case, I would have to respectfully disagree. While exponential decay of rewards allows distribution by PoB to continue, it either ends up a) putting an artificial constraint on price or b) unfairly dilutes early contributors. For a continuous PoB scheme, I'm not sure that any distribution would manage to satisfy both early and late investors (correct me if I'm wrong). The establishment of a market to trade the coins along with useful services is more likely to foster adoption.
I agree there is no distribution that would satisfy everyone.
In terms of participation, so far 335.9079 BTC has been burnt. Ignoring the USD/BTC rate, how does this compare with the initial offerings from NXT and Mastercoin?
It is impossible to know how many different people have burnt BTC for XCP though...