This design does improve stability at rest and also assists in fuel economy but the trade of is a less comfortable ride. The deep v hull is less stable when not moving but gives a softer ride underway. Deep v hulls track well while variable dead rise hulls tend to loose track with a wandering stern depending on the extent of dead rise variation. The variable dead rise hull can land harder in choppy seas. There is no perfect mono hull its all about trade offs. Some hulls are a compromise between the extremes Haines Signature claim this status.

I own a signature 632F and at rest it is definitely a very stable boat, one of the best I've been on in fact.  I can confirm what squalis says and it is a little harder through the chop, but no where near as harsh as the Ali's I've been on.  The 632 has a flat keel about four inches wide to help to get onto the plane, this adds to the harshness I suspect.

Not so sure about the wandering stern, I don't think mine has a big issue there.  I do get a bit of 200hp prop torque steer but generally it track ok.

This is very personal though, and comes down to what you're used to and what your looking for.  Only way to know is a sea trial.  Have spent very little time on a true deep vee to make that comparison.

the other issue I know some other signature owners have had is difficulty getting clear water for transducers.  I started with an in hull and had lots of issues.  Ended up resolving these with a thru hull.  Also have a LSS and a TM150 chirp on the transom and these are only really effective at very slow speeds.

Cheers.

It has variable deadrise and it's a bit harsh in certain choppy seas but the variable deadrise also helps it get up on the plane quicker and is a more efficient hull when on the planbe as there is less waterline length.

Mine has a floodable keel so she's really stable at rest. I haven't noticed any 'wandering stern' but it did take a while to sort out a good position for the transom mounted tranny.

I have got a 600 rf and it is very stable at rest but a bit bangy when travelling in rough seas.

I put my transducer about 800 mm from centre and can sound at 25 mph in 60m no problems. 

Variable deadeise hulls have been around for a long time it's just the evaluation of design. The variable deadrise can be built in different ways I like the new sig hulls there design is based on concave that much like a surfboard where it can channel air to provide lift and fuel efficiency the hull feels it rides a little harsher as it compresses the water more compared to.conventional convex style hull.As far as not tracking straight I don't find any issue with there rigs the plank also serves to help the boat plane easier and achieve a top speed when engine setup is done correctly , coming from a hi performance boat building background  we were building convex in to concave hull bottoms with planning planks and steps 20 years ago it's nice to see a major production manufacturer not do the same oldndeep v round bilge hull design.