Something like G Suite Business, gives me my own email domain , all their apps, unlimited data storage for $12 per user. Which if you have over 1TB worth of data, definitely worth it. It will cost you more for less features with Arq. Under 1 TB and no use for anything I said, Arq cloud definitely where it's at.
Seems like the unlimited storage is only valid if you have more than 5 accounts. Otherwise, it's capped at 1tb. Is that your experience as-well, or are you grandfathered in another plan?
It used to be that 5 user limit, but from what I can tell it is no longer.