Mate I used to own 2 vagabonds,one was late 90's model with 175 evinrude(no tabs) & one a 2001 model with f200 four stroke.(tbs fitted ,same hull still)Both had 250ltr tanks & theres no doubt that the lighter 175 rude (around 100kgs at the time )was a much better performing boat.The vag was designed to run twins so I thought when I bought a new one the 270ish kg yammie would have been the go plus it was the release of the first 200 four stroke.Of the 4 seafarers i owned they all liked to dip there nose in a short sea due to not much buoyancy up front even keiths(banana)23ft voyager used to.I'd maybe try a four blade prop for a bit of transom lift...try solas & if its no fix they usually will send you other props to try or refund your coin....failing that before moving tank forward put 80-100kg(fill esky with water)just behind helm seats mid ship & see if that helps.I'm no expert ..just my thoughts
Definantly put tabs on too as there subject to wind list & you can trim it so it cuts better.
I think there a great boat everthing is a compromise...Not a lot of boats will come close to a seafarer in a following sea...
I don't miss when your idling back to a mark on a cold winters morning ,its blowing 15knts head sea ...you look down at the gps then wooshka...a bucket of cold water comes through the clears...keeps you awake