AndyNZ:Depends. Certainly for most situations (e.g. typical two dive rec day) it was fine. However, the dive shop I do DM work for part time has a policy of only taking groups of four on O/W dives - so instructors/DMs "double dive" a day to get a eight students through their O/W dives in a weekend..... four dives in a day, sat looking for students with problems etc was quite frankly bl**dy freezing. If you are thinking of training as a DM you might end up in this situation!!
The Pinnacle suits would be fine for this in summer - but at this time of year, never again!
There's a brand of wetsuit called Trident (made in the same factory as Pinnacle and I think they're a wholly owned subsidary?) have the same merino lining but the outer fabric seems a little more robust.
If you're going to go down the drysuit route, I'd definitely look to buy outside of NZ. You should be able to claim tax back when you leave Holland which would make it a lot cheaper than the suits here (typically NZ$2500-3500).
I reckon a drysuit is definantly the best way to go but in saying that I know heaps of people that dive wetsuits all year round, even in Wellington.
Our store stocks Trident Drysuits that are trilam, come with an undersuit for $2000. They are a nice suit and hard wearing. Maybe thats a possibility?