We are also appreciating using Sellbrite more and more. When the shipping was down we had to manually enter address in our fedex account which of course is such a slow process!
We used to just use Amazon, but now we get better rates with our own FedEx account. So....then we either have to do it with Sellbrite or enter manually in our fedex account. Sellbrite is worth the money just in time savings for that one thing!
The other BIG things it's increasingly helpful for is keeping track of our inventory and making pricing or other changes across all our channels at once. It's been an investment of time and money but I can see the value now.
Oh, and lest I forget -- outstanding customer service -- which is essential to the whole thing. I did sign up for their premium plan (which I recommend) but I suspect they give outstanding customer service either way.