At the moment the older Go 530 is about £160. Which seems like a much better deal than the IQ XL @ £150 especially given the extra features included.
We went into Halfords for a demo (on their clearance stock) and the "kid" who got sent over was utterly useless, my wife knew more about the units than he did.
We started off by saying we'd like to see how good the voice commands and text to speak were... answer "they are not available on the 530"
As if by magic some little pixie had smuggled those features onto the 530 while he wasn't looking

He almost crawled under the display in embarassment. The best bit was we did the whole demo and not only did he try and push the garmin halfway through, when he switched it off the display read "Warning! Do not leave your TomTom Go 730 in your car"
It wasn't even the 530

(would've been a good deal at £160)
EDIT: We are going to pass on the Traffic plug-in and use the TrafficTV Iphone app instead. It seems to include more info and actual live camera streams for almost the same £35 cost.