Matching a inflatable non rigid Zodiac Mark II ST 2009 against a inflatable rigid Zodiac Pro 500 2011 means you're likely deciding between two genuinely different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
The power gap is worth calling out. Rated to 70 hp, the Zodiac Pro 500 2011 has a 30-hp advantage over the Zodiac Mark II ST 2009's 40-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load.
For family outings this is probably the sharpest distinction between the two. The Zodiac Pro 500 2011 is rated for 9 passengers, while the Zodiac Mark II ST 2009 caps at 7. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Zodiac Pro 500 2011 could be the deciding factor.
The Zodiac Pro 500 2011 has a documented top speed of 41 mph. Speed data wasn't available for the other model.
Bottom line: Choose the Zodiac Pro 500 2011 if your priority is putting more people on the water — it handles 9 passengers and at 15,4 ft it has the deck room to back that rating up comfortably. The Zodiac Mark II ST 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 7 that costs less to run day-to-day.