I'm just wondering if there's any interest in arranging/defining the magus's abilities so that you have two sensible choices after 7th/8th level -- one where a character continues on as a magus, and one where he swaps into the EK to emphasize melee combat.
Looking at the current class, I would make Medium Armor and Heavy Armor into arcanas, make Arcane Weapon dependent on the magus's caster level (as opposed to magus level), move Fighter Training down to 7th level, and install cool new, magic-oriented class features at levels 10 and 14.
The guy taking the EK/melee path would grab the medium armor at 3rd, the heavy armor at 6th, hang in Magus past 7 to get Improved Spell Combat at 8th, then swap to EK for the better BAB, secure that EK levels 2-10 will improve his Arcane Weapon. He'd lose a casting level and class features, but be able to out-fighter the pure magus.
I'm actually very fond of how easily the Magus can slip into most Prestige Classes without MCing.
I like that you can drift into Eldritch Knight to focus on the melee, but I also like how it can slide into Arcane Archer as well. I just wish there was an Arcana that let you cast your first level spells without preparation, so I could sneak one into Dragon Disciple... Heh.
I agree with your interest in allowing them to split their focus though.
Eldritch Knight fulfills the melee focus for them.
Who knows though... we have yet to see all of the new book.
There might be a PrC opposite the EK to shift towards casting instead.
There ARE others out there that trade attack for spells (mostly bard-based though).