Hi guys,I'm new here but have been on the Bertram site for years lurking. I have a couple of 20' bertrams(moppies),a '79 15 'whaler and for about 6 or 7 years a 84' - 19' Grady White Tarpon(also known as a tournament).I probably use the Grady more than any of my boats and really love it. I've taken it to the Keys a few times, ,fished the jetties at Fernandina, fish quite often off the Jekyll and St.Simons coast,but I mostly use it deep trolling mountain riverine type lakes for big brown trout.It still has the original Evinrude 115.My fishing buddy is a Yacht broker in Hilton Head and has found a slightly used 150 Johnson 4 stroke that he thinks we should get for my Grady.I am always inclined to go with his recommendation but thought I would come to the experts to ask advice.The 115 runs good and has been great but who knows when she is gonna crap out and it could be in the middle of a snowstorm in the Smoky mountains .I understand the 4 strokes are better for the slow trolling we do.Could I get some thoughts and opinions.Thanks in advance