X-cart works fine until Qualiteam engineers begin repairing something, then many other things break and it is an almost neverending story.
We had been running X-Cart for 3 years. Had to close our store because we had nothing but problems with X-Cart. Lots of integrity issues, Google said the Mobile Module has lots of issues such as the buttons being to closes to each other and gave it a very low ranking. X-Cart Tech Department told us to stop using the Refine Filters and Infinite Scroll Modules as they have issues. I highly suggest you don't invest a dime in X-Cart software. We had full Tech Support and they could not fix the issues. Some issues they said were not covered by Tech Support and wanted us to pay a ton of money to fix them. X-Cart Techs will blame 3/4 of the issues on your server host and try to get you to switch to their hosting. In most cases you will turn in a Tech Support request and get an e-mail within the following couple days saying they need more info to work on the issue. It does not matter how detail you make your request. We had some support request handed to personal that were heading out of the office on vacation. Over all experience with X-Cart was a nightmare each day.
I love xcart, their site is good, their products are high quality and the customer support is average to better, it is based in India or Russia (i think). If your used to MVC setups, its easy to get into the guts of the software, however it is based heavily on Smarty which is the only downside.