I still think the later models, with smaller motors, dirtied the premotor filter a lot quicker than the early models.
I ran a DC07 for years, and it very rarely needed any cleaning of the premotor filter. Aside from the extreme noise, they were actually very effective at filtering the dust. I think Dyson over engineered what was essentially a good design. More cyclones do not mean less filter maintenance, so why bother with so many? Personally I think it was solely for the sake of releasing new models, to keep sales up.
I still think after 2007, and the economic crash, Dyson started skimping on quality, with more plastic and less metal.
The backbones on the pre DC25 uprights were very sturdy with metal wands. These were good machines. Now, they are all plastic, and when I tried out a DC41 in Currys, I was disappointed how flimsy the backbone of the machine was, and also the more frequent filter maintenance.
People might think I'm a Dyson hater - I wasn't, up until quite recently, and I've owned and refurbed a fair few Dysons over the years. I think Dyson has just got too greedy and profit hungry now he's established his name, and his current offerings of all ball designs don't appeal to all. He should still be offering a wheeled upright - an upgrade of the DC33 if you like.
Also, with the move to Malaysia, his prices should have come down, to reflect cheaper production costs, but they have gone up, and I feel he has a bit of a cheek to ask for so much. He's made his fortune, so its time his machines became more reasonably priced.
[this post was last edited: 4/17/2014-07:15]