B G,
If you are to be believed, I guess you are with Bristow in Norwich. I am on the 139 at North Denes, and have to say that, to me, the 139 is definately the way ahead for the medium fleet on the North Sea, without question.
I agree they did get off to a bad start reliability wise, but most of the regularly occuring problems are gradually being ironed out by Agusta. The main cause of the two aircraft at Denes staying on the round for a lot longer than required recently on their 1200 hour checks is down to lack of CHC engineering management of large projects. When they finally do get them going the lack of spares/ support from HELI ONE is astounding. The first aircraft got half way through the check and then ran out of parts so the engineers sat around for a few days with nothing to do bar fit some cowlings waiting for parts to arrive!
To answer your question, when engineering is sorted, the 139 is reliable, and is at the moment quite the best aircraft you could hope to fly. When they get uprated to 6800kgs, the offshore companies will love them even more!