I can't say I've noticed AL drivers are significantly worse than others, notably black cabbies. Having been inside AL cars any number of times (my employer requires we use them in lieu of black cabs for journeys from the office) I know that the drivers are quite aggressive towards any other road user - it's not just cyclists, although from the saddle it will feel that way. I thik the drivers have a fairly rudimentary knowledge of London's streets, compared with a black cabbie, and they rely on satnav most of the time, which doesn't help.
As for cabbies, I find they are quite reasonable when they have a fare - they probably don't want to look an arse in front of a passenger, and wouldn't want a conrfontation which might lead to the fare walking away. When they are running for hire, however, they are quite a different proposition. One cabbie got really nasty with me in the City when my Brompton front bag brushed his wing - it's cloth for chrissake, it might polish his paintwork but it won't scratch it!
In any case, there are way too many cabbies in London - time to start restricting their numbers. There can be 4-5,000 of them trawling the City of London alone, a significant proportion empty, churing out their PM10s to no useful purpose. They also line up outside my office at the rank, engines idling and yet more PM10s.