i dont know what gfamr is but on all the neo2 based chips to boot a dvdr the toc size of the original that you use needs to be greater than the toc of the backup you are booting (or the same size).
as for -rw discs, as has already been said the ps2 can boot them BUT its not as reliable or as stable as -r and as with -r it relies on you using decent quality media, the cheapos just dont work well on ps2.