With an Eu2000i and a EU2000i Companion you parallel them with one pair of cables and a ground wire. The Companion has a 30 amp twist lock and has a 30 amp RV adapter. When we want to run the A/C we run both units. If no A/C, I'll run one generator.
If you get two units and one is not a companion, you can still parallel then, but you need a bit more for a parallel kit that includes a 30 amp plug.
As for reliability, you cannot beat the Honda. And if they need parts or service, you can find Honda dealers all over the country. Can you find service for a lesser generator all over the USA?
Ken