Updated.
Just returned from Italy with 2 new Tivusat Smarcam & Smartcards @ 85.00 euro each and I can confirm the following
a) Tivusat Smarcam does NOT work on Humax 5400, even with upgrade to Toh 3.4_Hot 11
b) Samsung DTT PPV Smarcam Does work on/off, as long as the decoder is booted on La7 and left to activate for 10 secs, then all is fine when running, switching to channels is no problem. If you switch the decoder off, you have to boot from La7 again!
c) Samsung (2) DTT PPV Smarcam tested and works 100% on any channel from boot and also reads the smartcard number, also very smooth and fast!
If you want to kep your current Humax or other Decoder and have a Rai Abbonamento, you can order your Tivusat Smartcard from Rai Tv on line, I think they charge 40 euro and purchase a Samsung (2) DTT ppv Smarcam on ebay.it from £50.00 inc delivery to uk = Total £80.00
d) The other option is to buy a Humax Combo 9000 & Tivusat Smartcard included for 150.00 euro, and this will save you all the hastle!