OK...I'll try this one...!
Having only moved back to Liverpool with a car post-bus-lane-suspension, I can't say I have a huge amount of experience of the system before they suspended them. I used to get the bus/cycle to school 11 years ago, when they seemed to be very useful, zipping past all the cars! (Although the direct route I cycled to school- Childwall Triangle to Blue Coat- didn't have any bus lanes anyway!) However, looking at the road layout as a grown-up driving around, you can really see how some roads could clog up in a major way with the bus lanes active (i.e. Picton Road ends up as one lane all the way from Wavertree Clock Tower to town), which could (and did) lead to massive tailbacks in the one lane available to all traffic, whilst the bus lane was completely empty a lot of the time. I imagine this is the sort of thing they're studying and analysing...!
It doesn't tend to have that much of an impact on me, as I tend to use the motorbike if I need to travel into the city centre at rush hour- the most annoying thing at the moment is going to other cities and having to remember NOT to drive in the bus lanes! :s I can't really comment on the impact on cycling into the city centre as I'm a little too far out for the ride to be comfortable (I do a very active job, and don't relish the prospect of riding home at the end of a shift), but to be honest, the route I'd take (Tarbock Road/Roby Road/Edge Lane) doesn't have bus lanes anyway, so it wouldn't make too much difference.
I imagine what we might see when the study ends in July is that some of the lanes may be reinstated at particular times. Without meaning to go too off-topic, if the rail fares on the city line were cheaper, I'd prefer to get the train into town anyway- the bus just takes too long, even when there's no traffic. When I caught the train from Broad Green, before the latest round of fare rises, it was just about economically viable enough for the train to win over the motorbike/car when I didn't cycle. Now that I'm in Huyton though (only two stops further along the line) it is actually pretty much the same price to drive and park in town.
Ian