Speed and performance are not a characteristic of "MOST" aluminum hulls. There are a select few hulls out there that do better than others, but they are also not inexpensive. It takes a good bit of power to move a big grizzly through the water; same for Alumaweld, Alumacraft, Waco, and a bunch of others. Having been around most of the major brands and a select few minor brands, I can tell you that you can take a 25hp motor, clamp it onto a Havoc and it'll go 30-31 mph with the correct prop; but take the exact same motor and put it on the exact same size Waco commercial-rated boat and it might muster 26 mph-if you're lucky. So saying that a 1448 will go X mph means nothing, at least not to me. It's all dependent on the hull.
On the O.P.'s boat, I would suggest one of the newer 25hp motors. From 9.8 to 15 isn't a huge jump. From 9.8 to 20 is an "ok" jump. Most newer 25hp motors are far superior to the 25's from just a couple years ago, and not much if any heavier than the 20hp. BUT, if you look around, the "old" 25hp and as well the 20hp and 15hp can be found dirt cheap, brand new. Local dealer is liquidating them to make room for the 2018 stuff, and with excellent prices.