I searched the definition of Participatory Economics, and I realised it sounds like Anarch-Syndicalism. It is still a "decentralised collectivist economy"! Relying on "Decision" by means of economic distribution is very dangerous! We cannot 100% predict the resource allocations and inventories, and the "nature" always betrays our decision/will!
Speaking of the self-management, it sacrifices "advantages of division of labour", causes a cut threat competition among these small economic agents, incurs a very high cost to obtain and protect the market information, and creates a bigger income and social inequality than comprehensive liberalism = capitalism (*) does (Who decide where and how those people in this system work?).
If the answer of the last question I asked you is a "democratic decision making process" (You may mean direct democratic), it will defnitely fail into the same problem of Athenian democracy which Hobbes highly criticised! The critical problem of direct democracy is that it always ends up with either a compromised unstable outcome or the outcome that an "orator" offers. It would avoid this outcome as long as the majority are highly rational and/or the the orator is very talented. However, I have hardly seen this kind of civilisation yet in any where nor any time period. That's why a certain degree of autocracy should remain and/or lassez-faire (spontaneously distributes human, phisical, and intellectual resources) should be encouraged! Comprehensive liberalism = capitalism equips both advantages of a certain degree of autocracy and laissez-faire. Thus, comprehensive liberalism = capitalism is only the best alternative!
All in all, capitalism = comprehensive liberalism is the most "natural" system where people "passively take" the situation for granted. J.M. Keynes claimed that we should intervenue if necessary but we must understand and follow the nature of ""market geometry""!
Marx (I know Participatory Economics is totally different from Marxism, I must mention Marx for those who frequently use the word "capitalism" to call and criticise comprehensive-liberalism) considered this system "always in the boom" and "always benefits" to bourgeoigie. But, Marxian assumption is totally wrong! He ignored the existence of "the cycle". Any economic system has a cycle. When "capitalism/liberal-economism" is in a recession, both bourgeoigie and proletariat suffer. However, capitalist system is the most controlable system among all the economic systems having ever existed! We must remember J. M. Keynes saying "Although I am not convinced by unconscious aristocrats, I am proud of myself as a bourgeoigie because I am not an uneducated uncivilised rough proletariat!" As long as freedom of choice and natural right are protected, and we are aware of business cycle, capitalism = comprehensive liberalism is the most flexible and ideal economic system, human-beings have ever seen!
(*) "Capitalism" is only the name used by Marxist to call "Liberal Economism" whose "Liberal" means "Classical Liberalism" or "Comprehensive Liberalism"!
P.S.
All in all, "any kind of socialism" is an opiate worse than religion.... As I have seen many mobs and hypocritic elites calling themselves as socialist, I recognise majority of these mobs are really spoiled, detached from the reality, arrogant (looking down all their opponents as "unintelligent"), and dangerous (always threatening our public safety by unproductive riots, ear-souring speaches, and pessimism which is very contingent to the other innosent people). I know you are never going to become as such. But, I hope you are never going to suffer from this disease of socialism...!