Josie:
Just to clarify I've used the PowerFlow collection System on my 2305 (Not sure the model #), and the Cyclone rake Commercial (Circa 2004). It has a 6hp Tecumseh engine on it and a huge fabric hopper. I got the dual casters.
The only possible advantage I'd say for the power flow system is it's more compact since it's mounted on the tractor but I wouldn't buy it again. It also empties very, very easily - The CR Doesn't - (Don't believe the videos). Again, a pain to unclog, clogs often, doesn't hold much compared to the CR, etc. Also, on the 2305 the mounts BOLT on, making using the 3pt a pain. These days I typically only use my Power flow system on the 2305 for leaf collection in the fall, I mulch all other times. I have used the CR on the 2305, a 3320 and 3820 with a 72" deck and it kept up will all of them no problem.
One other note on the PF system. It sucks a LOT of power from your mower. On the 2305 I didn't so much notice the power loss as the just about doubling (maybe more) of fuel consumption. Not sure how much HP it takes but it takes that HP all the time whether you are cutting a lot of material or not - As long as the deck is engaged it's using a lot of HP. Note that the fuel consumption on the CR isn't great either but at least it doesn't take any power away from the mower/deck.
If I was considering guying a cyclone rake (again) I think I'd get a DR model instead.The fabric bags clump the material. Unless it's dry leaves it isn't going to slide out like the video shows. You'll be digging it out since the sides 'pucker' outward and stop it from sliding. The DR has hard plastic sides which I think would really be slick to slide the material out.
I would also get fixed wheels instead of casters if possible. If you are used to a trailer and don't mind do it. The casters are really a pain in the *****. Also if you are trying to get close to a house, car, or obstacle you need to turn away very, very, very slowly to avoid whacking anything, you don't have that problem with a trailer type setup. I know DR offers that, not sure about CR. Also the caster tires wear out quickly since they oscillate from side to side.
The DR's have a lifetime guaranteed metal impeller that looks like it would do a good job (I know folks with it and they like it). I will say the impeller on the CR which they claim is pretty much indestructible is. Mine doesn't show much wear after all the use I've put it through and I don't think I have any chips or anything on it. You could blow crushed rocks with it all day and the impeller would hold up (You'd shoot a hole in the chute though...

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