I bought a Nitro 482 about a year ago, and while doing my research, I looked at a Stratos that was also in the 17-18 foot range as well. The Stratos dealer was also a Yamaha dealer, and they were able to show me a series of graphs indicating the performance of a bunch of bass boats with different styles of Yamaha engines (old 2 stroke, newer two stroke, four stroke). In every case, the two strokes have a much better hole shot and planing time than do the four strokes. This data may still be available on Yamaha's webpage.
Two strokes are also lighter than four strokes, and there are a couple of consequences from that: (1) you may have a slightly slower rig (overall) with a four stroke; and (2) the extra weight may reduce the maximum horsepower that you can put on your boat (further reducing your top end).
This is a long winded way of saying that I think two strokes are a better option for bass boats and for other types of boats that need to get up on plane quickly.
Now, the other question is old style two stroke versus an optimax-style two stroke. I have an optimax on mine, and I am a huge fan of it. The engine strarts like a car, it is much quieter than an old school two stroke, and the emissions are much better (from both an environmental perspective and from the perspective of somebody who has to smell it everytime you start the engine). Biggest downside is that optimax oil is more expensive than regular two stroke oil.
Hope this helps.
