I have used the Endurance/False life combo religiously, and it has saved my wizard's life more often than I want to think about. I also use the false life as ablative HP's in the begining of an adventure, where I will cast vampiric touch. At my level, the average creature we encounter won't eat thru the False Life badly, and I'll have a net gain in temp. HP's.
I thought that temp. HP's did not stack, but the only reference I can find is about Aid, and how the points from it would not stack. That could be just that you cannot double the attack and save bonus from aid, which is what it was refering to, but I would think if the Temp HP's were different, it would have stated so in the same example.