You're dropping from one extreme into another.
FYI
The 3.4 was the only thing we needed to create our own toolchain that was at least as performant (binary wise) as a commercial toolchain.
I was able to compile u-boot with the toolchain (buildroot based, powerpc-linux-uclibc-gcc) but the final linkcing failed (caused a segfault, Make error 321 or something).
For the time being, I use the ELDK compiler to build u-boot and the 3.4 based toolchain for everything else (including the kernel). I'll have another look at it in the next weeks or so.
[mleeman@gemini mleeman]$ powerpc-linux-uclibc-gcc -v Reading specs from /opt/barco/toolchain_uclibc_powerpc/build_powerpc/host_tools/lib/gcc/powerpc-linux-uclibc/3.4.1/specs Configured with: /opt/barco/toolchain_uclibc_powerpc/toolchain_build_powerpc/gcc-3.4.1/configure --prefix=/opt/barco/toolchain_uclibc_powerpc/build_powerpc/host_tools --build=i386-pc-linux-gnu --host=i386-pc-linux-gnu --target=powerpc-linux-uclibc --enable-languages=c --enable-shared --disable-__cxa_atexit --enable-target-optspace --with-gnu-ld --disable-nls --enable-multilib --enable-sjlj-exceptions Thread model: posix gcc version 3.4.1