Installing these don't compromise the integrity of the deck or effect the warranty. These guards were extensively tested by Honda and have been available for the HRX for many years. The steel is a very good grade stainless and should last forever.
I've seen bone-stock HRX mowers used by commercial operators and the decks were fine, but the wheels were shredded, due to scrubbing along curbs and sidewalks. Here are a couple with 150+ hours: