The old 150 and 200 hp V6 2-strokes with the same displacement have almost identical torque curves until you get to the top end of the rpm range. So there is little difference in hole shot or the ability to stay on plane. You will lose a few mph of top speed if you go down to a 150 hp.
I've been on overnighters with both engines (Yamahas) and I can personally attest to this. The 200 had a 19" prop and the 150 swung a 17". Seat of the pants felt like the 150 actually did better at lower cruising speeds as far as staying on plane in a chop. That was probably due to the prop though.
Now if you are comparing an old 200 to a new 150 E-Tec you can ignore my comments.