This cryptonote coin use to get stuck a lot as well.. but they had a good diff.. better then XMR (for smaller coins starting out..) I tried their diff for a few test models but a 90% hash drop took a week to fix.. and the final one I went with was only 5 days for a 90%.. XMR would take months in projected models as I didn't have the time to run real test on numbers like that..

http://explorer.karbowanec.com/en/