I mounted the SSQA last night - decided that I didn't want to wait. It seems to work fine on the LA504 loader on my B3200. In my opinion - it definitely makes swapping attachments a LOT easier than using the Kubota pin-on style QA. That's the good. The bad is that the SSQA weighs in at 78 pounds - and the pin-on QA only weighs 22 pounds. So you're taking a 56 pound hit to go with the SSQA. I suspect that the buckets are heavier too - but I haven't had a chance to weigh them yet.
Another think I checked is the location of the pin at the end of the loader arm - against the back of the bucket, on all three of the variations: direct pin on bucket, pin-on style QA - and SSQA.
For the direct pin-on bucket - there is 2 1/4 inches between the center of the pin - and the back face of the bucket.
When the pin-on QA is on the loader arm - there is 5 1/2 inches between the pin center and back face of the bucket. So adding the pin-on style QA pushes the bucket out quite a bit from the pivot point (this leads to reduction in capacity)
With the SSQA adapter installed - there's about 4 inches between the pin center and the back of the bucket. So the SSQA is definitely better than the pin-on style adapter in this regard.
The thing is - I believe with a better design - the SSQA setup could have the bucket with no more offset than a direct pin on bucket - or add some very minimal offset - like 1/2" to 1". The Kubota design is sort of "inefficient" With some better engineering I think they probably could have taken another 15-20 pounds out of the adapter weight itself - and also brought the bucket in closer to the pivot point.
It's a good solution - it's just not optimized as much as it could have been.