0.20.205 was just renamed to 1.0 so it is esentially the same release. The APIs have hardly any difference. 1.0 is similar to 0.20.2 with append & security features which basically means it supports HBase integration and can be used in enterprises.
We ported our jobs running on EMR on 0.20.2 to directly run on 1.0. All our jobs, whether they were using the new or old API did not have a single issue but ran correctly without us having to change anything. So I believe you should not face any issues.