Isn't there the problem where one pool having over 51% of the hashrate results in more orphans for other miners and pools?
My pool at
http://prospercoin.treasurequarry.com:37373 has just found its first block but it ended up orphaned. Not sure how worthwhile it'll be running a pool if one designated "official pool" continues to have the huge majority of the hashrate.
If that is correct, it ought to be near impossible to solo mine. But I have been solo mining Prospercoin with just one gpu and finding blocks as recent as yesterday ( February 3). I'll run a test right now. with a R9270X and 300 khash/s.
Test result: found one block giving 10 prospercoins within one hour. Three hours later no more blocks are found. The one that was found by then has 72 confirmations, and 'matures in 48 more blocks'.
Conclusion: solo mining is still feasible with this coin, even with us that do not have dedicated mining rigs, but just a pc with a graphics card.