I have to go along with Paulo on the helm balance issue. I've done three very light, wide stern boats, the two FlyTiger models and the one off ICON. All are very well balanced. As Paulo says two fingers, lightly on the wheel is all it takes to drive ICON. ...
Take any one of those wide ( L/B's below 3.4), lght (D/L's below 130) flat bottomed boats and heel it over 20 degrees. They roll bow down but the keel gets a nice angle of attack and the water sees a long, sliver of a boat. It's a very easy shape to balance. If these boats all had bad helms they would have corrected it by now. Similar hulls and similar frac rigs with similar keels and similar rudders they have to be able to figure it out and I'm certain they have. You can't win races in a poorly balanced boat. These boats didn't pop up over night as an experiment. They have evolved.
Any very light boat will have a more or less flat bottom but the ones with more flat bottoms are the ones (as you say) with large beam and big transom.
The boat I posted and the one was talking about has not by modern standards a big bottom neither a large beam, I would call that beam a moderated one. A boat like the one you seem to be describing is the Pogo 12.50 that has a beam of 4.50m with all the beam brought back which gives a large transom. The Arcona 410 has a beam of 3.90 and the beam is not brought all back, giving a moderated transom (by average modern standards).
The shape of both hulls in a superior view:
But of course this as to do with what you call a big beam or a big transom, anyone can have his own standards in what regards that.
Brent, the Pogo, the one with the big beam and transom does not have hydraulic steering, neither a wheel. It has a tiller, in fact two.
Regarding the boat sailing performance on the ARC, that is crossing the Atlantic right now, the only Pogo 12.50 is by far the fastest 40ft and has been battling and winning over a bigger racing boat, a very fast one, a TP 52.
This is a racing TP 52:
The Pogo is a performance cruiser not a racer and is making a Transat at the same speed as the fastest 55/60ft cruising boats.
I bet they have no problems with the steering