What Next
The 1999 KG limit is a paper limit not a safety based limit and I know of no private op Senecas which are flown to that figure.
You are of course correct it is technically illegal so that is a risk the pilot/operator has to take.
Of course I do not condone that I am just stating reality as to what happens in the real world.
Pilot/owners do not want to pay Nav charges, certificate at 1999 KG then fly to the normal certificated weight limits. Its a tough economic climate out there.
Regarding the famous Seneca porpoise. Yes landed on the nose or flat and they will start an uncontrollable bounce which gets worse until hey presto you loose the nosewheel and end up sitting on the props.
The only way out of that scenario is not to sit there like an involuntary passenger but to apply back pressure to the column and power and then resettle the aircraft.
But do not get in that situation in the first place! Apply loads of trim so you need a slight forward pressure on the column coming in to land and land mains first not flat or worse on the nose.
Flown correctly they land beautifully flown badly????
I would change your assumption on pilots who have or will land badly to bad pilots.
I have 2500 hrs on the aircraft and have never had a bad landing. That included a 90 degree 40 kt constant crosswind into Denham once over double the demonstrated limit and I am no SKY GOD!!!
So do not knock the Seneca Five it is a well tried and tested aircraft and a docile faithful servant.
Pace