Tekkit only has redpower because it is in 1.2.5, FTB also has a 1.2.5 version which also has redpower. FTB also has a much better 1.4.2 version which is awaiting red power. It also actually ASKED FOR PERMISSION from the mod makers.
EE2 and RP2 is much better than 1.4! And tekkit is going to update...
of course tekkit also have permissions! Tekkit have existed in long time and FTB short.
They do not have the mod permissions, perhaps some but not every mod creator agreed with it. Just because they have existed longer has nothing to do with it. Tekkit is by all means illegal due to the fact that they are not fully endorsed by the mod creators, this is practically common knowledge by now. I even recall that the modpack maker admitted he did not ask for permissions.
Also , EE3 and RP2 (what tekkit has isn't even RP2, at most it's a pre-release) will come to FTB 1.4.5, with less bugs and more awesomeness.
Also...when the hell is Tekkit ever going to update then? Practically ALL the mods are out for 1.3.2 already yet Tekkit is still stuck in 1.2.5