Yes, it did have problems a few years ago, especially regarding RAIDs, but it’s improved a lot since then. RAID5 still sucks though 😁… but I read the problem is finally been worked on (haven’t checked code, I read about it in a sub on reddit).

No, it doesn’t have something like zvol, it has the regular subvolumes (pools in ZFS) and you can assign quotas, the same as in ZFS. But, to represent itself as separate block device, no. And I don’t think this is something that’s planned, though I could be wrong (as I said, I haven’t looked at their git in ages).