Alan, I have not used the Seaward but we considered it - briefly - when replacing the alcohol stove on our 424. The Seaward seemed less elegantly finished and at least one model in our size range did not come with burner heat sensors, which I think is unacceptable. I also found the model we were considering had a thermostatically controlled oven. This seems an ''improvement'' to some and that''s why Force 10 started offering this as an option, as well. But I think this is another failure point, and definitely don''t find its needed on a well built oven. (We bake a LOT and find the F10 oven offers very even, controllable heat).
FYI we found the F10 3-burner model fit perfectly (tho'' snugly) in the stock fiberglass alcove in our 424 galley (we have the ''U'' galley) and have lots of swinging room. This is our 2nd F10 stove (I installed an earlier 3-burner model on a H-R 35) and we''ve been pleased both times. They could do a better job of making the battery holder, and making it accessible - this is what powers the self-light feature (which after 6 years, 4 living aboard, have all but gone away now). So...not a perfect product, but perfect enough.
Where do you sail your 424?