When two boats share the same hull type — in this case both the Zodiac IV 2009 and the Zodiac Zoom 400 SR 2008 are inflatable rigid designs with inflatable construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
The power gap is worth calling out. Rated to 350 hp, the Zodiac IV 2009 has a 320-hp advantage over the Zodiac Zoom 400 SR 2008's 30-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 IV 2009 is rated for 15 passengers, while the Zodiac Zoom 400 SR 2008 caps at 7. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Zodiac IV 2009 could be the deciding factor.
Bottom line: Choose the Zodiac IV 2009 if your priority is putting more people on the water — it handles 15 passengers and at 27,9 ft it has the deck room to back that rating up comfortably. The Zodiac Zoom 400 SR 2008 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 7 that costs less to run day-to-day.