981 is more modern, 3.4 engine is the same (well, +5hp) as the 987.2, electric power steering, newer PDK software too I believe.
To run, my 987.2 S PDK get 26-27 mpg mixed driving, manual will probably be a bit lower without 7th gear. Service prices are reasonable, 2 year or 20k mile intervals and ~£300/500 for minor/major at the main dealer. Mine has the warranty on (which you can transfer between private owners), it's about £800pa including breakdown/assistance cover. I've had the air-oil separator and high-pressure fuel pump replaced under that, but you are locked into getting all the work done at the dealer - so £300 for a new battery, over £1k for brakes all round etc.
There's a plethora of options available, so I'd go and see some examples and work out what you need/want/don't care about.
To run, my 987.2 S PDK get 26-27 mpg mixed driving, manual will probably be a bit lower without 7th gear. Service prices are reasonable, 2 year or 20k mile intervals and ~£300/500 for minor/major at the main dealer. Mine has the warranty on (which you can transfer between private owners), it's about £800pa including breakdown/assistance cover. I've had the air-oil separator and high-pressure fuel pump replaced under that, but you are locked into getting all the work done at the dealer - so £300 for a new battery, over £1k for brakes all round etc.
There's a plethora of options available, so I'd go and see some examples and work out what you need/want/don't care about.