I think you are asking about 'fretboard radius'... I don't build guitars, but I thought I'd post these links that explain what it is about for those interested. I'm sure our resident luthiers have the definitive answers. I did find an old guitar player review of the D-500 and D-250 which says both of those have fretboard radius of 16". Probably, most of them do.
Comments
Anyway, here are some links:
Fretboard Radius by Jimmie Leslie - http://www.musicplayer.com/article/fretboard-radius/Sep-06/23104
Guitar Fretboard Radius by Alan Ratcliffe - http://www.alanratcliffe.com/articles/radius.shtml
Gitane D-500 and D-250 Review, Jan 2004 - Guitar Player - http://www.sinomusic.com.tw/SAGA/D-500.files/D-500-DG-250%20Guitar%20Player%20USA%20%20Jan%2004.pdf
Radius Gauges - Stewart MacDonald http://www.stewmac.com/shop/Tools/Special_tools_for:_Neck,_fingerboard/Radius_Gauges.html
Cheers
Greg