In reply to 1poundSOCKS:
I think I'd placed my equivalent cam further down the route! There have definitely been a few occasions where I was quite glad to have the size 5 cam on my harness, all on routes at E1 or below. Large cams (say dragon 6 and above) are only useful every now and again but tend to make you feel pretty glad of having them, they're very much a useful thing to convince your mate to buy if you have a regular climbing partner, unfortunately I don't and I seem to periodically get coerced into climbing wide cracks.
My experience on central crack may have been coloured by the beta given by the locals!