Zena,
The benefit of remaining at MSA/LSALT until within the circling area is to my mind one which far outweighs the risks of going below it 10nm from the field - you don't tend to hit anything.
In Australia they only survey terrain within the circling area (out to 6.94nm for Cat E) to ensure obstacle clearance. Personally I'd be happy to descend to 1000 feet at night 30nm from some of the airports I fly to, but I won't for two reasons:
1) It's illegal
2) I THINK I know the area like the back of my hand, but I really don't want a single power line or un-noticed hill to prove my knowledge invalid.
I don't know how far from an airfield the JAA surveys but ultimately it comes down to insurance and discretion - why go low if you don't have to?
As far as aircraft performance goes, if you set yourself up early enough, descending to circuit height from the MSA/LSALT and completing a circuit within 2.66nm is no drama whatsoever.