I also bought the FireBear Improved Import Export Extension and it's enhancing the Magento 2 default products import. So it can be helpful if you plan importing products/customers/orders in your Magento 2 store, let's say based on CSV. But I think the tool is helpful if you have already the data from a different language/technology based platform and you want to import.
But if you are migrating intra-technology (from Magento 1 to Magento 2) I would recommend using the official Magento tools for Data Migration:
Concerning the SSH access, you should first check your company policy and see if providing access to a 3rd party vendor is allowed. Then, concerning the trust, I think the opinions are really split: some really trustable companies or websites might be a scam and some really not trustable companies with a poor presentation website might turn in the end to be correct. As far as I know about these guys, they are from Germany, so more details on their website. But in my opinion, you should listen first to your company policy. Good luck!