Thanks for that one, Div.
Did you and XH go tyre kicking of any other brands than the Pacific? In which case, what did you like about that over any others, or was that the only one you looked at? I've seen an older pacific (maybe 5 years old) and I dont know if the design has changed since then, but it looked like there were several stages to folding/unfolding (not ideal) and the fixed front wheel (probably the same system as on your old one) didnt look too handy for close quarter manoeuvring.
Ive had a good look at and play with a Trek branded trailer. The seating and harness system on that was pretty much the same as the Pacific trailer I saw, which is to say very basic. However, the Trek manoeuvres far better than any pram I've pushed so far, (It has two fully articulated front wheels like a wheel chair and is very stable) including the current model Valco something-or-other twim pram. The Trek folds in one move, not three like the Valco and the 3+(?) of the Pacific trailer. The Trek (at 11 kg) is also substantially lighter than the Valco and Pacific. It also tows beautifully behind a bike and the boy LOVED being in it for the short test ride I was able to do, but pram functionality is our most important concern.
I was expecting there to be more in favour of a 'real' pram over a 'compromise' solution like a bike trailer, but the 'only' thing I can see that the bike trailer doesnt do as well or better than a conventional twin pram is the harness system and seat 'reclinability'.

These are generalisations I know, but here is what I've found at the moment:
**Dedicated twin pram benefits
Similar or narrower width
Better Harness
Reclinable seats - better suited to newborns

**Well chosen Bike trailer benefits
Lighter
As, and probably more manoeuvrable
Easier to fold and pick up
Much better weather protection
More storage space
(And of course, you can tow the kids behind a bike)

I have been told there are trailer brands out there that now have reclinable seats and/or are suitable for newborns as well as toddlers (when in pram mode, not while towing) which, with the benefits of trailers mentioned above, would be our ideal situation.

Any further thoughts on this would be much appreciated, people.

Thanks again, Div.
-Mick