"I've just got back from a bad PNG trip to Kavieng, so I've a few reservations about returning to PNG so soon."
Kavieng is the place I would least like to dive again in PNG. My one trip there was my one trip to PNG where the cost and time were least warranted.
"is anyone else able to shed a bit more light on the style of diving in Rabaul/Walindi. I checked out the Febrina site however it was not that helpful."
As you leave Rabaul it is likely you will dive Duke of Yorks and Fathers before heading to Kimbe. The outer reefs of Fathers have some really nice bommie diving so you may get some pelagic action there, but that is really going to be about it unless something out of the ordinary occurs. I think the reef around the Atun is really productive and Two Tanks, if the water is reasonably clear, can be a dramatic if comical scene. Outside of that it will be mostly macro, although reef fish shooting is always there to be had.
I've been to PNG a number of times now and except for Kavieng have always enjoy it. And I am returning in '07 and '08. I am not normally one of those people who can shoot macro, and macro, and more macro. It justs gets to me after a few days. But shooting macro in PNG is just a lot of fun.
I always look at PNG as a fun trip, rather than a productive one, because it is a bit disheartening to review your shoot and see 90% macro images. But I always go back because PNG has so many critters and they are so accessable, that "in the moment" it is some of the best times I've had shooting images underwater.
Not that it will ever be as outrageously enjoyable as Darwin on good day, but there is something to be said for shooting a Ribbon Eel, while Mandarins swim in the rubble next to you, as the Croc Fish yawns behind you, as the Leaf Scorpionfish sways with the shallow water and the true Clowns watch from their little anemone homes. And all this happens in a couple square meters where these are the obvious, can't miss seeing 'em, subjects. You are suddenly faced with the notion that you have to decide what to shoot first, or whether to shoot any of it, because you just realized you haven't even begun to hunt yet. 
It is very hard not to have fun in an environment so rich in quality and diversity........even if it is mostly macro.
Earlier this year I did the South itinerary (Solomon Sea) out of Rabaul and I think that once Alan gets that itinerary down pat, it may well be the best route for the most different photo ops of all PNG itineraries I've been on. It had phenomenal macro, excellent reef fish populations and quality wide angle opportunities, given good water----which we were not given for much of the trip 
But like you, I want more than macro, and it is the itinerary that I believe is most likely to quench all my photographic wants in PNG waters.