F200/F175 or smaller?

[verch]

I'm looking for a little help. I know the classic Seacrafts don't do well with a lot of weight on the back of them. I have a 1988 Tracker/Seacraft and just sold the Yamaha F115 off it yesterday. It had 500 hours and was 13 years old. I figured I'd upgrade while I could still get a fair price for it. It only pushed my 20' Open Fisherman about 30mph and to my surprise after installing a fuel flow sensor last week, it was burning 11.9 GPH at WOT to achieve that. I live in Louisiana and a lot of my ridding is in rivers and canals where its very comfortable to cruise at 50mph+. I had my eye on the F200 inline 4 Yamaha or Suzuki. Both are under 500lbs and by old 115 was 440lbs. Didn't figure there would be much difference there. I believe my boat is a little heaver and longer than the classic 20 footers and felt like it could handle the extra weight but would like your opinions. I;m not much on 2 strokes as I believe they will eventually fade out and depreciate quickly. Any advise would be greatly appreciated.