How are you expanding capacity? With traditional software raid I'd need to fail every drive and replace them one by one with identical higher capacity drives which requires several rebuilds from parity which means a long time and massive I/O loads and high risk of unrecoverable read errors just destroying the whole array in the process. It's easier to make a new array and move data over...
I used to do what you're doing. Last 6-7 years I've been running mirrored setup so I could expand by just adding a new vdev. Rebuilt it twice when I upgraded to significantly larger disks.
As I mentioned ZFS on top of LVM seems interesting in terms of features and flexibility. But reliability-wise... I'd like to run a more proper test setup to gain some experience before I'd trust it.
https://raid.wiki.kernel.org/index.php/Growing#Expanding_exi...
Btrfs has a more flexible block allocator but its parity implementation is still unreliable.