hello, aleko. i am a home inspector from the western new york area. the old cloth, 2 wire wiring is kind of dangerous, in my opinion. as stated earlier, the cloth gets brittle and can crumble with the slightest of touch. with rehabbing the place, you are going to disturb it, for sure. then, you have exposed wiring. fire hazzard. not to mention, a lot of this old wiring is made of aluminum, not copper, therefore, the heat it will carry without fail is far lesser that the copper type wiring. if you have an overload somehow, and the breaker doesn't trip, you are going to have a fire. the gfi's have to be grounded, thats the whole idea of a gfi. the g stands for GROUND. with the two wire system you have, where is the ground???? you don't have one, hence, your gfi's could not be hooked up correctly.
i agree, the $15k sounds a bit steep for the total rewiring job. i would shop around for the best deal you can find, but i would definitely do it. yes, of course it would " pass inspection" as is, if a home inspection was about pass or fail, but it's not about pass or fail. its about the condition of your home at the present time. and at this present time, the wiring is working as designed. is it safe??? no, but it's working. a good inspector would have told you that it is in working order, but has many potential dangers.