I've had very good experience with the HPDI 200. And I haven't heard a single bad report from anynone running the 2.6 litre block motors - that's the 150 HPDI and 200 HPDI standard and V-Max. The 3.3 litre block motors are different (250 and 300 HPDI) and there are numerous reports across Europe and the US from owners suffering blown pistons.
Over a long period of running the 200HPDI I've had very good fuel consumption - about 1.1 litres per nautical mile, the very worst being 1.2 litres per nautical mile when most of the time was spent flat out at wide open throttle.
The V-Max engines are only available in long shaft - no XL or XXL, so make sure your transom is suitable. I believe thay come with low water pickup - check http://www.yamaha-motor.co.uk/produc...di_150-250.jsp