I think Root does have more airflow, but I do have a soft spot for Dual Cyclone machines, not least because they are easier to strip down and clean, and don't do what the DC07 in your picture does (and I've seen many examples of it!)
I like all Dysons from DC01 to DC33, DC44 is another nice latest Dyson
Root cyclone is better I guess, but does get dirty!!!
The DC07 malaysian modela are screamers
I may just be very biased, but I'd say dual cyclone. When well engineered I've found dual cyclone machines to filter better than cheap multi cyclonic machines. IMHO once you get past 2 cyclones I think it simply impedes airflow and creates unnecessary and unpleasant noise.
I always found the DC04 to be fantastic at filtering even fire ash, our next Dyson a root cyclone DC18 needed extensily more filter maintenance, the Radial cyclone DC38 I have seems very good possibliy better than the DC04,
It's funny how the Dyson "Core Separator" technology (aka Level 3 Root Cyclone) seems to have become a dead-end technology. Maybe the patents have expired.
There is a lot to be said for the DC04. The DC33 - years later - is running on many of the same parts anyway. That says a lot.
I like DC07's but they do have their cyclone problems.
On the DC14, they went back to filter in the top of the cyclone and they have more in common with the DC04 then the DC07.
The DC33 is a facelifted DC14 with less metal and more plastic.
There is a lot to be said for DC04's. It was good, solid, reliable engineering. We still sell them pretty much every day reconditioned. Can be fixed nice and easy like a Morris Minor. What's not to like?
The Dyson Medic photo above was actually taken in our shop on our techs bench (all the crap in the background gives it away - he isn't the tidiest of blokes). Angus was down that day and we happened to open a customers machine that "wasn't sucking very well". When we saw what was inside, everyone pulled out their phones to photograph it. It was to become the poster boy as to what DC07's can suffer from.
Have to agree, the DC04 was a good machine, and the colours were good too. My favourite ones were the DeStijl, and the Limited edition pink and purple. They were better than the DC01 in that they had washable filters, and they had clutches too.
Its interesting how Dyson has gone backwards over the years regarding filter washing. On the DC07, it was recommended to wash the filter every 6 months, but on the later DC50, this is now every 1 month. The DC07 was actually very good at keeping the pre-motor filter clean (well, those that were de-rooted were anyway). The less powerful they have become, the more dust that gets to the pre-motor filter.