I've been using OneSaas on behalf of a client for about 3 years now. It works well to sync the ecommerce store with QuickBooks and also the shipping system, saving a lot of time vs having to do manual data entry.
Occasionally there is a glitch, but whenever I contact the support team, they always respond quickly and get the problem fixed. We had a little issue the other day where a couple of orders wouldn't sync due to a change in the product SKU. Troy responded right away and fixed the problem - everything is working splendidly again.