knob and tube wiring. Full gut job or is surface mount wiring okay?

[Eric Hathway]

I just got a home inspection done on a 3 family and they found 90% of the electircal to be active knob and tube. It is a fire risk being in the insulation in the attic so if I moved forward with the deal it would have to be removed.

Has anyone heard of removing it and rewiring with surface mounted wiring? From what I hear it would be half the cost and in my case the seller might agree to have it done.

Any thoughts?