Nubian, a very good summary.
Just a note. The "B3+" is a direct application of the EC130B4 onto the 350 B3. The EC130B4 was certified with dual channel FADEC and EBCAU due to the design request(ap the dual hydraulics ala 355) and it was applied to the b3 which is why all later models are B3+.
The performance is the same but the characteristics different due to the dual fadec vs single. Little things like when GOV warnings will come on inflight and when not is the big difference. on the B3+ the amber or flashing will come on on shutdown where as for the same failure on the B3 it will come on inflight due to no redundant channel to take over ap the B3+. Due to the rotor rpm variance power demands and delivery differs. On the b3+ one seldom see the rotor rpm range fully utilised due to the smaller TR inputs, on the Ec130b4 it is a lot more noticeable.
Most important difference-DO NOT TOUCH THE TWIST GRIP IN A OLD B3 WITH THE BATT OFF!!!!!! Due to single channel DECU it can not self calibrate and confirm the metering valve is in a known position-the b3+ with it's dual channels can check, dispute and confirm as there is 2.