I have a new 23S with the SSQA. I also have a set of pin on pallet forks. So I have experience with both.
If I had to pick one I would say the SSQA without hesitation. I also just picked up 2 more buckets, so I have to switch between 3 buckets, pallet forks, and an auger. That's a lot of pins to swap around.
I've been a mechanic for 25 years, am still able to lift heavy things and roll around on the ground without a problem.
And swapping the pin on is still time consuming and a hassle. Especially with the newer attached stand that comes with the loader.
However, you do lose lifting capacity with the SSQA. It's fairly heavy, plus it pushes the weight slightly further from the pins (further you go the less you can lift).
Which is why I have a the pin on forks, for heavier things I can't lift with my SSQA forks.
There are several other ways to get slightly more lift as well. But you need to proceed with caution there and understand what you're doing. The BX is very stable on the ground, once you start raising extra weight up high it can drastically change the balance. And you can potentially overstress the loader arms.
I also don't agree that if you need to lift more you automatically need a bigger tractor, FWIW. Other considerations go into which tractor besides just size.
I don't know if the newer bucket has less capacity. I do know anything you can lift with the 23S isn't going to stress the bucket that comes with it. I've buried the bucket in piles so deep I couldn't lift it and had to back out more times than I can count.
The nice thing with the SSQA is it's retroactively installable. You can buy the pin on loader and add the SSQA to the loader down the road (the SSQA pins onto the loader), though it may be a little more expensive that way.
There's also a aftermarket different quick attach available from AI2 that's lighter than the Kubota one. But it doesn't work with SSQA implements, only the ones designed for it.
One last thing. I believe anything that pins onto your loader will also pin onto the newer loader (they have the same pattern). The only difficulty is the stand for the newer loader requires different pins.
I actually have a thread about that, I'll try to find it and link it.
So if you have other pin on attachments you want to use you can unpin the SSQA and pin on whatever, then remove and reinstall the SSQA as needed.
More of a pain, but an option.