I've got a 99 Brava TD100SX and I get about 47-49 on the motorway, and about 45 round town, although it seems to suffer a bit more if I do lots of short journeys. Performance is 'good' when on the turbo and there is lots of torque when you need it ie when you are moving at a reasonable speed. Its 50-70 feels very lively but I havn't timed it. Make sure you get the red key.
I'm not aware of any 'features'of this engine that need attention, like cambelt failures, and the only issues I've had in 40Kmiles are that the rear washer pipe fell off, but was easy to fix, and the drivers electric window motor failed, again easy to fix but needed a new assembly (£55). Touch wood, it seems very well screwed together, no leaks or rattles and no knobs have fallen off!