Android : APK Expansion Files - load directly from obb or unzip?

I'm developing an app with as3 air for android.

The app is bigger then 50MB so we are using the expansion files option.

I uploaded the expansion files and managed to download them with the app.

My question is, should i load the files directly from the obb using this native extension for air as3:

http://www.zooom.at/app-shop.html

Or should i unzip the obb on the first time i open the app, save the unzipped files to a different folder and load from there, using fzip?

(i read that if i rename the obb to zip i can unpack it)

http://codeazur.com.br/lab/fzip/

what is the best approach?