Tiny progress, I made a cheap support using old rods from a table umbrella to prevent the chute rotation hoses from rubbing on the ground. I had those hoses made this long because I was wishing to tilt the blower angled to the left or right. I had them long enough to make a loop that could enlarge/tighten given the angle of the blower.
Also I've used the blower enough to start having an opinion on it.
Power requirement
First, the 16hp Onan is not overkill at all. It does the job but it wouldn't hurt to have more power. Not saying an upgrade is mandatory but it's probably the minimum power for this blower. It could be used with less power but it would be necessary to not use the blower at it's full capacity; move slower and/or don't take full height/width.
I am also watching when the chute is angled the thickness of the snow coming out of the spout, it gets to about 3 inch thick, I find this quite impressive to see!
Vibrations
So far I didn't use the blower at full throttle. I don't think I need it and sometimes I get quite a lot of vibrations, I don't know yet if the RPM has an impact on this or if it's when I overload the blower. I don't know if the auger or the turbine is causing those vibrations but so far each time I simply have to slow down and it will stop.
Noise
The chain is quite noisy, may be it's too slack or the sprockets are worn. May be I'm simply not used to this noise.
Distance
Throwing distance so far is way enough for my needs, somewhere around 25 feet away, more than this and I would have to manage a lot more where the snow is going to avoid damaging my hedges. On the other hand I thought it would be able to throw further than that, again so far I didn't exceed 3/4 throttle.
Uplift stop
John Deere provide an uplift stop for their blower, I don't have one yet and I am not decided if I need one. It probably has to do with preventing damaging the PTO shaft, I will have to look into this. Would be safer to have one if the blower gets lifted by the snow bank.
Shaft support rod
Another thing John Deere provides is a support rod for the PTO shaft. I don't have one and I don't know if it would fit my long PTO shaft but I might have to look into that. For storing the shaft I simply put it up and turn it right until it gets supported by the blower. Is this support rod for storing the shaft? It could be to help aligning the shaft when mounting the blower? An annoying thing is to attach the blower to the tractor, the PTO shaft is too long to be installed after attaching the blower, I must get 2-3 inches away from attaching, place the PTO shaft on the hitch's lower part and then I can move to the blower.
Chute rotation cylinder cover
I don't have the OEM plastic one and it must be modified to fit the 270° rotation modification therefore I won't spend the ~150$ they ask for it only to modify it! Given I store my tractor/blower in my heated garage this is not really causing any issues, it gets full of snow but it melts between each uses. So far nothing prevents the cylinder from doing it's job and I don't think anything could be damaged by not using one. It could be a problem if ice chunks or misc stuff (wood, brick) gets over the blower. I will still make one, mostly to have less snow that I cannot clear before moving the tractor inside. I try to keep my garage as dry as possible therefore less snow inside is less water everywhere. So far I always use the blade to push the snow to one side of my driveway then I blow it and often the snowbank to blow gets way higher than the blower.
General
It's quite a big project to fit those John Deere accessories to the 1655/1855 but I am absolutely glad I did. May be not having used a blower that was so worn (rusted) but otherwise I would do it again. The blower and blade are great, it's easy to use and the tractor is a joy to use with those accessories. I hate even more the snow throwers (1 stage) like the one on my JD 214 and think the snow blowers are way more suited to my needs. I must admit the blowers are way heavier but with a quick hitch this is not an issue.
Oh also "fun" fact, with the counterweight I have and the actual weight of the blower sometimes I can feel the tractor's frame twisting on it's length if I lift the front wheel to rake the ground clean and the blower is not on a common slope with the rear wheels. I definitely will try to avoid doing this to prevent damages to my frame but I can understand the guys adding a frame under the tractors to the rear axle when they install a front end loader; there is a limit to the strength of the frames.