Full disclosure: I am yacht broker with decades of experience, educated at MIT in Naval Architecture & Marine Engineering, a yachtbuilder and licensed mariner for over 40 years. Because of my experience, I have little use for 90% of the practicing marine surveyors and always recommend an appropriate surveyor to my clients from a short list.
So,unless the previous survey was done by a member of the varsity under my supervision, I would always suggest engaging your own surveyor. I insist my clients are present at the survey and seatrials as they are an opportunity for a Buyer to learn a lot about the vessel...of more value that what will be in a written report.
I would not ordinarily worry that a Seller would not budge on the Selling Price. I always advise my clients (Buyers) when making an offer to not have an expectation of survey adjustments unless there are really big surprises like the bottom is badly blistered or the genset is junk. Your broker, should be knowledgeable enough to have a good handle on most minor issues that will be found at survey. There is no better way to upset a Seller than to make him/her feel like they are being nickel & dimed following survey. Further most brokers do not understand that if a Conditional Acceptance is made following survey, the vessel is no longer under agreement and the Seller is no longer obliged to sell you the vessel under the terms of the Purchase & Sales Agreement. We are definitely experiencing a Seller's Market at present so it's not adviseable to miss out on an otherwise good boat that is fairly priced and meets yoru needs.