Replay Gain: A how to informational

hello,

i want to to buy a sansa fuze and i 'm very interested with replaygain ability but  i have some point that are not very clear for me,

i know there are two implementations for storing replay gain information in mp3 tag

1 - the standart way id3 v2.4 , RVA2 frames

http://www.id3.org/id3v2.4.0-frames

all my music collection is tagged with rav2 frames

(the files are not modified , replaygain info are just stored in tag)

2 - sadly foobar2000 implement is own non standart replaygain : information are tagged in TXXX: frames

which implementation use the sansa fuze ? rva2 replaygain or foobar replay ?