Frank, you know, I dont't like really to add a configure script, because I think it complicates the install instructions and add another thing to maintain, without real advantages to the distribution. Also, stock DJGPP and Mingw users don't install bash, sed and fileutils.
Probably a new user, doesn't edit makedefs.grx at all and try make -f directly, this is ok. The same user probably will be bewildered with the configure questions.
Anyway, I want to listen more GRX user's opinions.