If you are looking at the 25 you may find the 28 is not much more money. With that said, I have spent a great deal of time offshore in a 2510 with twin 150 and 2520 with a single 250 and a 2820 with twin 250s. All of the aforementioned are deep vees. Quite frankly, the boats will take more than you or I will. In head sea, don't expect to do more than 20-24 knots. In a following sea, quartering sea or beam see she will fly. Just remember your are not in a narrow beam center console sitting far aft. If you are looking for a 30 knot boat, the Parker is not for you.
I would suggest that you try get a ride with someone and spend some time on a Parker before you pull the trigger. Where are you located?
I have had my 2520 DV with a single 250 since 1998 and if I had to do over, I would purchase the same boat. I am not a canyon runner but I do make three to four trips a year to the 30 line. I watch the weather and if it blows up, I throttle back and enjoy the ride. My buddy had a 28 and was taking a beating on the ride home one particular day. Rather than run hard he decided to slow down and enjoy the ride by doing a fast troll. He ended up with a 65lb Wahoo off the Jersey shore. If you have any questions, feel free to ask.
Brad