my opinion, on a small engine its got to be Turbo all the way. The efficiency of a turbo just means it will suit the small engine so much better.
Superchargers traditionally are more suited to big V8's. Although its strange to see that some manufacturers are dumping power adders on the top end cars and sticking to the old increase the capacity method. Ie the new Vauxhall VXR8 they are dumping the supercharger option on the 6.0 and just dropping in the 7.0 litre.
speaking of small engine and turbo, heres one for ya Paul,
Fiat : FIAT SEICENTO 1.4 UNO TURBO ENGINE!