A dilemma has been encountered

I finally got my three supervisors to go over the thesis draft and comment on it. One thing that all three said was that I should not use the active voice. In my undergrad years I was always taught to use passive voice in technical writing, but here I was taught to use active voice, especially when writing a dissertation. Guy's supervisor, Tim, is a huge supporter of using first person so that it is clear what was done by me and what wasn't. Joe Wolfe also agrees:

If you are writing in the passive voice, you must be more careful about attribution than if you are writing in the active voice. "The sample was prepared by heating yttrium..." does not make it clear whether you did this or whether Acme Yttrium did it. "I prepared the sample..." is clear.

The active voice ("I measured the frequency...") is simpler, and it makes clear what you did and what was done by others. The passive voice ("The frequency was measured...") makes it easier to write ungrammatical or awkward sentences. If you use the passive voice, be especially wary of dangling participles. For example, the sentence "After considering all of these possible materials, plutonium was selected" implicitly attributes consciousness to plutonium. This choice is a question of taste: I prefer the active because it is clearer, more logical and makes attribution simple. The only arguments I have ever heard for avoiding the active voice in a thesis are (i) many theses are written in the passive voice, and (ii) some very polite people find the use of "I" immodest.

I wrote my entire dissertation in the active voice. My supervisors all told me it's my choice, but they recommend switching to passive voice. That would mean going over the entire thesis and changing everything: a lot of work. They should have told me this before I started writing...
What do you reckon? Does the active voice really sound that bad? I can't decide. I just want to be done with it!