If you can get a look from a firm like that which you respect, there will be other firms out there who don’t have a process that’s nearly as onerous. I’d punt them and never look back.
Believe me, a lot of firms look like wonderful places on paper or in their descriptions of themselves when trying to hire, but scratch the surface, and you discover everythign is screwed up big time. This is just a sign that something is wierd there.
And where there’s smoke, there’s usually fire. You might sign on and then you get a note saying "our parent company reviewed our offer and decided that it was too generous for you, I’d really like to pay you what we told you, but my hands are tied. Really, something is amiss there.
Numi’s got a good point that if they really are a top-notch company and you got this far, there’ll be others who like you, too.