David, the Webasto heat exchangers are long-lasting, but since they’re made of steel, they can corrode over time. If your leak is external, it’s a better situation than having a leak into the exhaust system, but either way, it’s worth fixing.
You can repair it using any method that works for you, and you’ll be good to go. If you ever need a replacement, new exchangers aren’t too expensive, and you might even find one from a salvage source.
Best of luck with the repair, and enjoy your trip!