Greetings CL.
I can defintely say that servicing will be costly. For both.
When I bought these items, I had already factored them in, just like any piece of unique work.
Having experienced servicing both AHCI and Patek/Lange watches over the last 20 years, they are both costly. No way at the moment to compare on the same scale though.
Maybe, the worry is whether these watches can /cannot be fixed. My personal answer is "yes". Both watches are far less complex than many really old watches/clocks I have seen, in terms of parts/materials/etc...probably less costly to restore than a some really old porcelain, oil paintings, cars, aeroplanes, so on. With available machines and programmable cutters etc..some really small parts can be fabricated if needed. So far, on both the Opus and MBF, the parts are not made of any difficult to manufacture materials.
Costly in the future, but definetely sustainable.