I recently had mine changed after 5 years, didn't realise the time had passed, it had only done 7,000 miles. Also had the alternator belt looked at and it was beginning to split, so may be worth looking at when you do the cam belt.
My VIN is 5D640649 so the ECU should be programmable however pscan shows the unit as an ABAutoLiv NOT a RC5EC5. Is this because it was a programmable type?
I have just fitted a passenger airbag to my 2005 MGTF and I am taking it to an MG garage to see if they can reconfigure the ECU to accept the second unit using T4.