Both the Triton Boats 1550 Crappie 2009 and the Triton Boats 1756 DS 2012 are modified-V designs, both built in aluminium, so 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?
Both boats share a closely matched power ceiling - 40 hp for the Triton Boats 1550 Crappie 2009 and 40 hp for the Triton Boats 1756 DS 2012. Real-world performance will come down more to which motor is actually bolted on, its load at the time, and whether it's a 4-stroke or 2-stroke setup.
For family outings this is probably the sharpest distinction between the two. The Triton Boats 1756 DS 2012 is rated for 5 passengers, while the Triton Boats 1550 Crappie 2009 caps at 4. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Triton Boats 1756 DS 2012 could be the deciding factor.
Bottom line: Choose the Triton Boats 1756 DS 2012 if your priority is putting more people on the water - it handles 5 passengers and at 17,0 ft it has the deck room to back that rating up comfortably. The Triton Boats 1550 Crappie 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 4 that costs less to run day-to-day.