I personally think it's good value if you look at buying a stock 1.4 engine, gearbox, and then converting and uprating it all to a proper turbo with box too cope.
The esseesse versions are different between 500 and Punto. The variations are the parts that are upgraded but essentially the engines are the same afaik?
The Punto 'esseesse' upgrage changes are (engine wise):
??Garrett GT 1446 turbocharger ??
boost pressure from 1.3 to 1.5 bar
new water and oil pipes to the turbo
new exhaust manifold, heat shield,
complete injector rail
MAP sensor
boost sensor
modified catalytic converter
larger diameter exhaust
new intercooler pipework
adapted radiator pipe
new water pump
wastegate valve
BMC air filter
new engine ECU
The 500 Abarth esseessee mods are only BMC air filter and remap!! (there are other mods in the kit, but not engine wise)
Abarth Grande Punto esseesse: 180bhp@5750rpm, peak of 272Nm@2750rpm.
500 Abarth esseesse : 160bhp@5750 rpm, peak of 230 Nm@3000rpm
Normal Abarth 500 produces 135bhp@5500rpm, peak 206Nm@3000rpm
So if it's out of a 500, then it will make no odds if it's esseesse or not. It will if it's a Punto.
Should be easy to verify with the seller though. A 500 will use an IHI RHF3-P turbo, a Abarth Punto will use a Garrett GT 1446. Not sure if the esseesse uses a different turbo or not?