I was set to make 2 migrations from Prestashop to Shopify. The first one went OK - still with one major issue.
The 2nd one is still running after the payment was confirmed more than 20 hours ago. They kept promising 8 hours of maximum. But now after those 20 hours we still have around 5.000 customers and 42.000 orders to go.
So if you ever wonder to ask the livechat of a time estimate - be careful. They are seriously just filling you with some piece of crap to make you buy.
AND for some extra they just told me to fund 655$. I did that. But afterwards I did found out that I bought insurance for the migration, which I didn't really wanted.
I can't recommend Cart2cart.