I have BigDecimal objects serialized with BlazeDS to Actionscript. Once they hit Actionscript as Number objects, they have values like:
140475.32
turns
I discovered that BlazeDS supports serializing Java BigDecimal objects to ActionScript Strings as well. So if you don't need the ActionScript data to be Numbers (you are not doing any math on the Flex / ActionScript side) then the String mapping works well (no rounding weirdness). See this link for the BlazeDS mapping options: http://livedocs.adobe.com/blazeds/1/blazeds_devguide/help.html?content=serialize_data_2.html