The reason that the Grob Tutor was chosen was due to the sky highprice that BAe wanted to charge for the Bulldog spar life extention and at the right price would have been the logical option.
Having had a look at the job myself and consider BAe overpriced it by IRO 400% I can see why the bean counters arrived at the Tutor decision, after all who would by an overhauled twenty year old car at the same price as a new one.
Its just a pitty that BAe failed take on board the overpricing message until the Govenment had to chop up the Nimrod outside their office windows.
Those old lags who dont like the Tutor should remember that most of its problems have been a result of the equipment spec that was drawn up by the MoD, the Hoffman prop was a lighter design and not the favored item of the manufacturer (the MT prop was ) and ten years down the line the fleet was grounded until all the Hofman Props were replaced with MT props.
The Grob while not a classic aircraft is more than capable of carrying out the task at a price that the govenment finances can afford.