The ETEC 25 weighs more than some of the 20hp 4 strokes. Hard to believe given that it's a 2 stroke motor, which to me the only advantage nowadays of owning a 2 stroke is a little lighter weight. ETEC shoots that right out the window, IMO. Yes it makes 25hp. And that might be attractive for a heavy boat with some heavier loading.
I've run some 15hp and 20hp motors at different times on my war eagle 1548. I wasn't opposed to the 15hp, and actually I was impressed that it ran 23 mph but it was an absolute SLUG getting on plane. Took about 8 seconds from idle to plane. The 25hp takes just under 4 seconds. The 20hp was a little faster, 25 mph, and on plane a little bit quicker (7 seconds) but the 15 and 20 are the exact same motor with the 20hp having 5 more horsepower-which really shows from 4000 RPM up. Below that, felt about like a 15. These are Yamaha's so keep that in mind.
I ran a 1448 Lowe for a while with a Tohatsu 20hp. This was about 4 years ago. It was a slug, hard to plane, slow top end, or should I say slower than I would expect. With 2 of us in the boat, it would not plane at all unless the 2nd person moved his/her weight around enough to get on plane. It was not a "fun" boat at all. We commonly fish a spot that's almost 3 miles from the ramp and 3 miles displacing water takes forever to get there...seems like an hour. Much more fun when it'll plane out! Oh and something else worth mentioning, the tohatsu 20hp power tilt is just that...just tilt. It won't power tilt under way. I thought it would be nice to have but only if it would TRIM under load, which it won't. That hurts both time to plane and top speed both because you have to adjust the trim pin like any other manual tilt motor, to find a happy medium between good holeshot and good top end.