FWIW, the character that is effectively a gestalt fighter/mage is the Abjurant Champion. As I stated, the classes that do at least slightly stagger the casting progression and/or the hit die are at least a start towards balance. The EK, for example, is far closer to balanced than the Champion although a quick comparison to other classes demonstrates that it's not nearly there.
It's all well and good to say "yeah but I just want to buff myself for combat". Ok, great. But you don't need level 9 spells for that and you really have no business having them with a BAB that is better than a rogue or a monks. All that's well and good, yet, you still do have those level 9 spells and the Wizard class was built with the lowest hit die and BAB for a reason -- the spells are *that* powerful.
On whether a 10/10 fighter/mage is as powerful as other classes or not, I'll grant you that some synergy is lost. However, such a combo is still quite effective. You don't have to have Wish. Such a character still has a lot of great spells and with ready access to buffs and an excellent BAB end up with combat durabilty and damage that are quite competitive with a rogue or monk of the same level. I don't comprehend why you should expect more than that except that there is an inherent mentality that "if I'm not the most powerful character in the party then I can't have fun". Multiclassing is about give and take and yes, sometimes you give up synergy if you go for a build that "has it all". If you need to have just as good of buffs as the pure wizard in the party then what's his job? Why do you expect to be just as good as him and also be almost as good of a tank/warrior as the fighter? Where the heck is the bard in all this? Or the sorceror (who is casting the same level spells as you if you go wizard and without any combat ability whatsoever)? Heck, what does the cleric do but be a healbot?
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As for those who are "ignoring me". Have at it. I'm providing an alternative view. I'm a DM and I'm also a professional game developer (albeit video games, not pen and paper). Balance is important to me and I have a lot of experience creating game systems. The term "viable" in the title meant to me "what is viable gameplay-wise" and I'm just offering my opinion on that. An opinion that you can take or leave as you will.