The LT10 is about $650 more, but that gets you front and rear decks standard. I fished my buddies 15-4 before and after he installed a front deck. You definitely want decks and not benches. The fish-ability is much much better.
I also think the LT10 is a better hull design because of the wider transom. The transom on the 15-4 is soo narrow that I'd consider it a design flaw. It makes it hard to get it up on plane, if you try and trim the bow up any you're liable to take water over the sides near the transom, and it squats on the pole if your motor is too heavy or your angler isn't heavy enough. They tried to fix those issues with the LT10 which is a redesign of the 15-4.
I'd rather run my 13 in any kind of chop over a 15-4. The wider transom allows you to move weight back and get the bow up.