Sebi, are you sure your circuit works?
The current-sensor transistor should be a PNP, with the emitter on the left and the base on the right.
In this way when the base goes 0.7V under the emitter, the collector source corrent to the resistors. With a NPN, the current pass from the base to the collector through the PN junction, and this is not correct.
Also you are using the other transistors as a darlington emitter follower, in other words a configuration that put the last emitter at 1.4V under the first base. It is ok if you want a power supply, but in this case the transistors have to be used as a switch and for this application it is used a PNP transistor (or a P channel Mosfet).
Polyswitch and similar are fine, but they are slow and you loss a few volts (they have to heat for breaking the circuit).
Seyyah, think about a circuit that switch off the power and try to restart every few seconds.
Pay attention the limiter is able to charge the capacitors of the circuit you are powering, otherwise it will not start.
Sorry for my English