Hello Dieter,
The buses generally seem to be successful. There were initially problems with the Orion VII lead-acid batteries needing early replacement and Orion replaced them under warranty with Lithium ion batteries.
Also there were early reports that the fuel savings were not up to expectations but that seems to have been caused by them being allocated to suburban routes rather than the stop-go-stop services in the city centre.
Hamilton received their first hybrids in 2006 and ordered more in 2009. Toronto has more than 750 in service with the first vehicles delivered in 2006.
Regards
Michael Taylor
Binbrook, Ontario
http://www.michaeltaylor.ca