I have been building "The Gimp" from source since the pre 1.0 version
BUT for "raw" images ??????
the current gimp is 8 bit only
it can not use 16 bit nor 32 bit images ( nor 128 bit images)
for RAW images i use "Gmic" from the TERMINAL
http://gmic.sourceforge.net/
there is a gimp 8 bit image ONLY plugin
for LARGE image data sets ( by LARGE i do mean a image greater than 8 Gigs in size)
and just large ( 2 to 8 Gig in size)
i use Nip2/Vips
( vips is also a terminal image library )
http://www.vips.ecs.soton.ac.uk/index.php?title=Nip2
i DO NOT !!! use imagemagick - except for Graphics-magick that Nip uses to open and save formats)
Gmic has replaces IM for me