motor weights, too much?

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been researching motors for repower in the near future. looking at something between 150 and 200 hp. boat is 18 sf. looking at yami and suzuki. all motors are weighing in between 465 andf 475 lbs. i have an older (92) merc offshore now which i believe weighs 410 lbs. i like how the boat runs now. not being too concerned w/ planing at low speeds, is that extra weight going to be a factor? rarely run w/ more than 3 people (usually 2 counting me) and boat is not overloaded w/ gear (it is an 18 ftr after all). i did build a 35 gal livewell on it and it has a 48 gal gas tank, though its rarely full. any thoughts are appreciated. im getting $ back from uncle sam for the first time ever and figure ill sink it into our floundering economy.