According to the following chart, Era Free should be avoided as it has brighteners and enzymes. <A href="http://www.pinstripesandpolkadots.com/detergentchoices.htm">http://www.pinstripesandpolkadots.com/detergentchoices.htm</A>
Enzymes can be helpful in cleaning but they may cause irritation in some sensitive babies. Optical brighteners make whites appear whiter by staying in fabrics and reflecting UV light. The fact that they stay in fabrics mean they can build-up and possibly cause build-up issues in diapers (ie stink!).
That said, brighteners and enzymes are very very common in the vast majority of mainstream detergents and yet most cloth diaperers use mainstream detergents with no problems. Charts like these can be useful for someone who is already having problems or needs to switch for whatever reason. But I wouldn't take everything written there as written in stone, plenty of people have lots of success with detergents labelled 'avoid'. Unless you specifically want to give the soap nuts a try (they are great!) then I'd recomend just keeping things simple and sticking with what you're already using. Then, later on, IF you have a problem then you can consider switching. Just remember to use only 1/4-1/3 (1/2 at the very very most) of the 'recomended' amount. And an extra rinse at the end of the cycle is also often useful.