We refinish alot of these decks every year and the timber oil looks fantastic. Would highly recommend it. Not too sure what kind of stain the contractor is looking at, but it has to be a hardwood formula. An average stain won't have the penetrating power for a denser wood like mahogony. If you would like to look at another product check out
www.messmers.com. They have a hardwood formula for mahagony decks. Just did one this week.
As for the maintenance, no way to avoid redoing it every 3-4 years at the maximum. Maybe more like 2-3. There is no product that will give you a longer life, just the nature of the beast...
www.experiencedmp.com