I've got a Delta two-bag jobbie, similar to the Axminster and SIP ones. I think mine has a 1HP motor - it's supposed to pull 8A but I'm not sure if that's peak or continuous. The motor plate is damaged where the power rating is, but it's physically a big motor about 1 1/2 times the volume of the one on my table saw.
Newer 439s now have a round nozzle, which may help a bit, as part of the problem is making the chips go round a sharp bend straight off the block. I hacksawed through the nail across the middle of mine (as welded there by Kity), and similarly removed the cross-shaped obstruction in front of the fan on the extractor. Both helped clogging a lot, so now it usually doesn't. Before it was as bad as you describe. My DX has a substantial steel fan, which will "mulch" any long shavings without clogging. All the obstructions did was allow shavings to wrap round them, giving any clog a head start.
The other thing that helps a lot is to try to keep the hose as flat (horizontal) as possible. My DX isn't man enough to suck chips far uphill, so letting the hose run along the floor was a no-no. It's still a bit awkward, as the inlet to the DX is at waist height, pointing downwards (the fan is horizontal). So I've got some rollers made from plastic wastepipe suspended from the beams in the ceiling by galv fencing wire, and the hose sort of lopes along those until it gets to the extractor. It's a PITA switching over from one mode to t'other. It certainly wouldn't work if everything was tidily plumbed in with permanent pipe.
I don't think it would run all that well without any extraction, as the shoulder in the extraction chute would make it block up, particularly when thicknessing, as it has to chuck the chips upwards against gravity. It's a bit underpowered as a P/T but I paid very little for mine (and had to refurbish it), so I can't complain.
The other thing I did with mine was block up a lot of annoying crevices, holes and gaps in the frame underneath the thicknesser table. The stand has a flat top, and previously chips used to build up in the space for the height adjustment chain at the bottom - a real nuisance as it would eventually gum up with chips.
I use it rarely, but like you I'm really glad I have it.
E.
