After the test migration and some consideration, I purchased the full support option. The technical support is very responsive and satisfied all my request. It took 10 working days to tune and test the migration. They made a number of test migrations, until I was satisfied, then they immediately started the full migration. This final process lasted 9 hours, exactly as forecasted, then everything was ok: from taxes to price tiers, from category images to external images linked inside the item description. So: a really good job. I only wished a 24/7 ticket service, instead of working days e-mails. Anyways, a very good service, reliable and recommended
Lorenzo