Steel, wood or aluminum

The issue with metal boats in general is that poorly installed or maintained electrical systems are an enemy. It's not as much about "corrosion", although they will oxidize and blister. It's more critical about the creation of batteries in the water via stay currents, bad grounding, mixed metals. That's the case under the boat, in the water as well as inside the boat in the bilges and crevices. An aluminum boat likes aluminum parts. Beyond aluminum you use bronze or quality stainless for through hulls, seacocks, and essentially all fittings below the water line. I use Schedule 80 pvc above it...

What material is your current boat made of?
Any issues with its build materials?
Mixed metals? Metal fuel tanks? Wood window frames? Wood/balsa coring?
Possible mini lessons may be examples of what to expect in larger projects.

...I should have also added, that quite often the metal boat's enemy is the marina or the boats adjacent as well. If you're concerned about maintenance, well, maybe owning isn't for you. But to own a metal boat requires a fastidious attention to maintenance. That doesn't mean it's expensive, but it is top-of-list.

Yep, Brother rtrafford has a great point. I have witnessed many issues due to boats next door or near by. This may seem little until somebody else's stray currents have ate up your hull. You may never realize this till next survey.
Oh, proper alloy/metal hull surveys usually cost much more.

When it comes to collisions (like a shipping container or a rock), thickness matters, and even the steel boat (as well as the FRP) can fail. Yes, if a collision is imminent, I'd prefer to be atop a steel hull rather than the alternatives, but that's also why we go overboard with life safety, epirus, ditch bags, sat phones, spots, and trip tracking monitors. Because **** happens out there to even the best build or best prepared.

I chose mine because Burger advised that me that the owner, leery of aluminum for the first time, changed the spec of the build at the last minute, increasing plating from 7mm to 8mm. I then developed a plan in stages to re-plate and reinforce sections that over the decades had been exposed to abuse. You cannot own a boat without planned maintenance incorporated into the upkeep. Even modern FRP can be suspect as builders cut weight.

If you're approaching a boat purchase keen on avoiding maintenance, maybe charter? Yeah, I removed my teak decks and rebuilt them with nida and FRP. I eliminated some teak trim. But boats need to be maintained, or you pay the price on resale or even face a complete inability to sell...

We know, Sister Judy deals with fine boats, fine people with very fine check-books.
Also an outstanding author, broker and contributor.
I hope I do not up-set her here;

I am none of these but my 48 year old, 58 x 18 plastic boat, has been on a beach, tapped some rocks, has hit and been hit by big and lil stuff (good thing I haven't painted her yet) and has proved near bomb proof.
Lots of cruising and was our home for many years.
Not to bad for an old phart from the swamps on a red-neck budget.

I may be wrong here but I feel the OP is not looking for one of those fine ships mentioned above.
I hope not a 50 year old boat either.

OTOH; If he can afford one of those fine ships, maintenance and maybe crew, then the material questions are moot.
And he needs to call Judy.

Find something you like that will work for you first, hull material may be further down your priority list.
Your surveyors will be a large part of your purchase also. They will guide you further with the hull material and maintenance required.
Surveyors will become great and long term friends, so hire from the better shops.

I used nidacore, had the sheets laminated both sides with a fiberglass skin. Bedded them down w 5200. Glass taped the joints. Glassed over the entirety to build up thickness. Fared and painted. Great outcome as it added strength, waterproofing, and R value. Holding up well after 6 years or so.

That is going to be hard replacing a D-49. That is a nice boat.

Re-read post #17 and why would you want guest on board?
Guest mess up everything ☺☺

We had four kats cruising with us at one time. Were currently anchored out with two.
Our son has moved off and got married (I tried to warn him). His cabin is now the wife's pantry. That leaves the bow cabin for fishing & diving equipment.
Yep, no room on a 58 x 18 for guest, just two kats.
Life is good.