There can be some real "red tape" disadvantages to documentation that may lead you to forgo it if a bank doesn't require it.
I had a documented 46' cutter that my late wife and I used to live aboard. We were co-owners. When she passed away, I applied to have her name removed from the document so that I could sell the boat. The Coast Guard would not issue a new "free and clear" document -- even though the ship's mortgage had been payed off some years earlier -- because they claimed they'd never received a valid satisfaction of the lien statement from the lender. The bank, on the other hand, claimed they had indeed sent such document and provided me with a copy. The Coast Guard lawyers refused to accept it because they said it was not from the "lenders of record." The bank from whom I'd originally gotten the mortgage had been sold twice to larger banks, and each time the administration of the loan was passed to the new bank, an assignment document was issued making the new bank the agent for the loan. The problem was that the loan had been packaged -- along with 70-some other boat loans -- and sold to three giant insurance companies as an investment instrument by the first bank many years ago. Even though the loan assignment documents -- which I had to track down -- assigned agency for my loan to the new banks, the Coast Guard had the three insurance companies listed in their official record as the lenders of record, and their lawyers would not accept a lien release that was not signed off on by the three giant insurance companies who knew nothing of the matter.
What a red tape nightmare! Every time I exchanged documentation with the Coast Guard, it took them two months to respond, and I could not sell the boat in the meantime. Finally -- after two full years of back and forth -- a lowly but sympathetic clerk at the Coast Guard documentation office diligently tracked down the required signatures, and I was issued a new, clear document.
Whew! I had just about given up hope.
Don't get yourself entangled with bureaucracy if you don't have to.