When the texture pack doesn't cover a certain mod it just uses the default in 1.4.7 as well.when you're using an ever evolving modpack, it's kinda hard to use a texture pack. Although I suppose with the 1.5 update textures all go into their seperate files, so if your TP doesn't cover a certain mod, it's textures will be default rather than purple square
Also, I became too used to Sphax with tech mods (especially the ores) and can't use default. I also hate how the IC2 machines look in default. I play with default textures in vanilla though.