One would hope that outgoings on a SC would be pretty low at least for the first 5-10 years, and I'd certainly not expect any corrosion work
Comparing like for like, it is worth noting that a brand new metal
CofA plane will also have low maintenance costs, through not needing airframe parts for the first 10-15 years.
I bought a new TB20 in 2002 and my airframe related costs to date are around a few hundred quid in total, over the 8 years.
Of course there were other costs, but they would have been the same if the plane was on the LAA (unless you want to disregard a dodgy-crankshaft AD, which I guess one can do
).
The reasons why the 1970s hardware tends to have silly-price annuals (a friend was paying £7000/year on a syndicate C150) are
- most CofA owners are not "engineer/DIY types" and just want a plane they can leave at some company, and they don't want to get involved (so they often get shafted)
- old planes tend to have corroding airframes and need airframe parts replaced, which are universally ripoff priced
- some maintenance companies have used the EASA regime to invent bogus costs and practices
One can dramatically reduce one's Annual costs by a careful initial purchase and a subsequent micro-management of what is done to it, and a very careful choice of who does the work (and the biggest factor is having a hangar where freelance engineers are allowed to work) but most CofA owners don't want to spend their time doing that. So they pay through the nose...
Obviously a 1400kg MTOW IFR 4-seater will have higher overall costs than a 600kg VFR 2-seater, and you would expect that given the massive difference in mission capability, but a lot of the operating cost difference is due to the owners of the former being unwilling to get their hands dirty, not down to LAA v. CofA.