Both the Triton Boats 1657 SS 2010 and the Triton Boats JT-17 2009 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?
The power gap is worth calling out. Rated to 65 hp, the Triton Boats JT-17 2009 has a 25-hp advantage over the Triton Boats 1657 SS 2010's 40-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Triton Boats JT-17 2009 carries 22 gallons versus 12 gallons in the Triton Boats 1657 SS 2010. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
Both boats are rated for 4 passengers - a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.
Bottom line: Performance buyers should lean toward the Triton Boats JT-17 2009 and its 65-hp ceiling. If fuel economy and quieter running matter more than top-end speed, the Triton Boats 1657 SS 2010 with its 40-hp rating is the more economical daily driver.