I admittedly don't know very much about the larger Grady White boats and my 228 Seafarer is tiny in comparison, but I'm very much a numbers guy and do what makes sense with regards to just that... the numbers. The Grady White website no longer gives the "performance data" on a 330 Express with twin F250's on it as it looks like they increased the horsepower ratings years ago but they can be found elsewhere on Google and other sites. For comparison purposes, the GW website says the 330 Express with twin F300's will go 44.6 mph @ 6,000 rpm while burning 51.7 gph of fuel and the optimum cruise is 29.9 mph @ 4,200 rpm while only burning 24 gph of fuel. With twin F250's the GW 330 Express will do a top speed of 41.6 mph @ 5,600 rpm, although the website doesn't give the fuel burn numbers, and they found that a comfortable cruising speed was 28.5 mph @ 4,000 rpm. I have to imagine with those numbers that the F250's will likely do better on fuel economy at WOT and likely even at optimum cruising speeds. For me personally, 41.6 mph is as fast as I need to go in my boat, especially if I was in a 33' boat or even larger and imo on a larger, heavier boat anything over 35 mph or so is just going to be for bragging rights.
The claim for my boat is that it'll do 45 mph as well, and maybe someday I'll test that theory out but it seems to be a waste of fuel, money and I honestly don't need to go that fast in the event of whales, marine life, logs/deadheads, obstructions and so on. It sounds like the twin F250's will definitely get the job done, just depends on the other things like the bow thruster, generator, how often you imagine you'll use them and so forth. I personally like Garmin over the competition, but that's a personal preference. I have to imagine that for a 33' GW that a bow thruster would definitely come in handy rather often and the issue with having someone install one on the newer boat for you would be the time frame as well as parts availability. Is everything in stock or are the parts potentially backordered, and I'd have to assume that just about every marine shop is going to be a minimum of 2-3 weeks out during the months of June, July, August and even September? If I were in your shoes, I'd double check the older F250's, make sure they don't have the dry exhaust corrosion issue, even though I believe they're past the years that had them, buy the older boat, run it for a season or two and if you don't like it then you could always sell it and likely break even at the very least, or even make some money off of it. Good luck!
Grady-White Express 330 33-foot express cabin boat: Deluxe seating, cabin amenities and interior lighting, a premiere saltwater sportfishing boat.
www.gradywhite.com
Grady-White ups the ante with its latest design: a big, burly express with outboard power.
www.saltwatersportsman.com