I'm probably a bit biased but will try to help your cause. One that I recently deliberated over as well.
Perry's are exceptionally well built boats; Lagoons are not. That's a fact. Lagoons are, however adequately built in most areas. They don't break apart quite as easily as some CF self appointed "experts" frequently assert. The L400 has proven to be durable and many have circumnavigated, as have Perrys.
The used Perry 43s on the Australian market will tend to be older and/or worked harder for the same money
as the L400s, so which one will give the most maintenance
issues in the future is a moot point.
In my case the decision came down to design. Both are proven, safe and sea kindly, with good bridge deck
clearance and the ability to store and carry a live aboard cruising load without having to go minimalist. Both have mini keels and sail drives, the Perry 43 usually has/needs larger engines. I'm sure the Perry43 has the edge when it comes to sailing ability but not by as much as I originally thought. Perhaps the ones I have encountered have been sailed by skippers with even less ability than me? (Hard to believe!)
The design differences that appealed to me (us) were the following L400 features that the Perry just didn't have:
-galley up design (big one for my wife)
- wide, flat decks uncluttered with turning blocks and lines
- the deck level helm
that gives an unobstructed view to all 4 corners without having to peer up through a hatch
or craning to see around the side of the cabin
windows that give superior visibility and less heat buildup
-engine compartments accessed via large sealed deck hatches rather than via disturbing rear bunks or through a hatch
in a shower
-a bulkhead between engine
compartment and living areas.
that is aft (quieter) and don't require one to climb over the other to exit
I know that many, many catamarans have happily sailed the world without these design features and some will vehemently disagree with my choices. Good luck to them. Moonos, you will also decide what suits you and your crew. Either boat will be great.