I've owned both a v20 steplift and various 20 seacrafts (two seacraft seafari's, one seacraft 20MA, and one 18 seacraft) in the last 10 years. They are both excellent boats. v20 is a bit larger and has more room. I now run a 23 seacraft which is a great boat too.
V20 is a great stable platform for fishing. In a head sea the ride is really good. Quartering will knock your fillings out. Following sea can be downright dangerous when the bow digs in. Overall it's a great boat. I fished my v20 40 miles offshore more than a few times. I stuffed the bow once on stellwagen bank and knocked the windshield into the cockpit. I would have never sold the boat except that I moved cross country.
20 seacraft is like a magic carpet in small chop. It's really a bay boat (so is every 20ft boat except maybe the bertram). Quartering . . . you can get the boat to pound if you don't use tabs to roll the hull a bit. The boat tracks nice straight in following seas. Anything over 2ft seas will put you airborne if you are trying to go faster than 22mph. This boat can get you in trouble, b/c it'll handle some pretty big water, but it's not the best decision to be out in there in this little boat. You could push the 20 seacraft very well with a 90hp - 115hp . . . if you get one DO NOT put a heavy motor on the back. 400lbs is about the max you want to do with a 25" transom. with a 20" transom I would stick with an inline 6 tower of power (275lb).