Good comments, both of you.
As I read and think more about the original question, I feel very lucky to have the 27 foot '73 boat I have. I've sailed it for almost a year now, once a week or more, and it's yet to surprise me with a complicated or expensive repair. It was maintained well, and I try my best to continue the process, and in the end I think it could serve me well for years of local daysailing and cruising.
In an older boat, I think that's the best case scenario. As noted, after a boat is 10 years old, it all comes down to maintenance as to whether the boat will sail or not, and if it will drain your wallet or not. That's why the "too good to be true" boats can be very expensive traps.
That said, for more than local daysailing and cruising, I think the stakes go much higher. The stresses from real coastal cruising (months at a time, partially offshore) are much higher that what I put on my boat. I read a lot of local stories about local cruises of 1-2 months on older boats that end with very expensive repairs being needed. If I had quit my job to cruise, my plans could be radically changed by a sudden $15k essential repair, being on the hard for a couple of months, etc.
So, for smaller boats and smaller goals, I feel that there's no question that a used boat with the very best maintenance history possible is worth the money, even if you pay extra for the superior past maintenance. For larger boats and larger plans, I think there could be a law of diminishing returns, where even new systems (if poorly installed) could lead to ongoing headaches, expenses and problems. In this realm, my sense is that being able to afford a boat that is 5-8 years old, with excellent maintenance, could provide significant benefits if you have serious and immediate goals.
New boats can have real problems, and a "five-year-old" boat is no guarantee of reliablity either, but my sense is the odds are improved. A boat 33 years old, like my 27 footer, may also be excellent shape and have fully updated systems, but there seems to be a lot of possible issues based on how well the work was done and problems not yet discovered (like hull-deck leaks when the boat is stressed in ocean swells).
But hey, it's all a process. From an odds perspective, maybe it's just better to own a series of boats, carefully learning from each, instead of trying to hit a home run with a major boat loan and a new or almost new boat. I still like the idea of careful, affordable steps to larger boats, or just sticking with a paid-off and enjoyable older boat for years until a big jump can be made. I just don't want a big boat with so many surprise problems that I can sail because of time and money issues. As noted at the start of the thread, I've learned about too many cruises that have never occured because of cost and time and older boats.