Don, I don't have any experience in Roamer ownership, but I have been around them in various marinas and boatyards for many years. Steel ones that is, no aluminum.
The small amount that I have heard about them is that many of them had a coating inside the bilge resembling automotive rustproofing. Down deep by the keel water often gets trapped under the coating and they can rust along what would be the garboard strake.
But they can be fairly easily repaired. It does cost money and involves the haulout and associated costs I talked about earlier.
And especially in salt water, electrical corrosion is a factor. I believe that most models came from the factory with a system with a control box that managed the minute electrical charges to address the problem.
And I also wanted to add my 2 cents about weight. I recently looked at a somewhat rundown but potentially beautiful 37 Roamer with twin 427 Ford's, which is a sweet running setup.
And while fiberglass Commanders might weigh nearly as much as a similiarily sized Roamer, this boat weighed approaching TWICE what my 35' Mahogany Commander with twin MLR's weighs.
Great for cutting through the waves, but imagine the fuel burn.
And I always wondered about sinking. A Roamer would have to sink like a stone. I've seen many wooden cruisers towed in by salvage companies over the years and they will sometimes ride with the water level at the main deck or with it slightly below the surface with more area underwater aft where the engines are. So some of them will actually "float" with a breached hull,if you can call it that. At least it would give you something to hang on to until help arrived.
Oh well, we're not supposed to be sinking them anyway!
1953 35' Commander "Adonis III"
1970 23' lancer project