I'm a small retailer, selling a bit over 20K a month, with about 70% of it on Amazon, 20% on eBay and 10% in other channels. I originally started with Sellbrite 2 years ago, first on their $49.00 plan (which they no longer have) then on their $89.00 plan. One of the reasons I signed up with them was because they had promised 2 years ago that they would have Sears, Rakuten & New Egg "very shortly". They finally delivered a few months ago, but only partially. You have to first create the listing, then you can link it to your existing listing, so if you want to manage anything other than quantity (like change pictures and such) you can't. You can only do that with Amazon, Ebay, Shopify and possibly Big Commerce. Another shortcoming that they've been promising to fix is that you can't "Kit" something, so if I sell a 3PK of an item I have listed on Ebay as a 3PK, it there's no way to correlate it to the individual items on Amazon, so I have to manually "fulfill" the item. I had an issue earlier this year where there was a problem with my Credit Card and they couldn't charge it, so when I went to renew, they told me I HAD to upgrade to their new plan at TWICE the price ($189.00). After I cancelled, they offered to let me back in at $129.00 and I only agreed to do it because of the difficulty in moving platforms. If I were starting fresh today, I'd definitely go with either Ecomdash or M2EPro, both of which allow Kitting and Bundling along with multi-user so you don't need to give your employees your username and pw.