Yes they are basically a 20i reseller, so performance is exactly what you get at 20i or any other 20i reseller.

Currently I have one dev site and one live site, with the right caching plugins I seem to get good speed. As they currently don't offer the WordPress plan with the stack cache (which they want to introduce at a later stage at extra cost). I can't say if that will improve speed even more.

They say they are in it for the long time. Should I trust them probably yeah. But should I host my customers websites on it ? I don't think so, with my own sites I only have to account to myself, with my customers sites I have to account to my customers.

How am I going to tell my customers, sorry my hosting provider closed shop, which I of course hope won't happen.

So I am sitting on the fence, go directly with 20i or one of their resellers at a monthly fee, or trust my sites and customers sites to makershost.io and hope for the best.

Unless they have a clear plan how to make it sustainable I really have to think about it and maybe reconsider. Running a business has monthly overheads (salaries etc.) Unless you get monthly paying customers to cover those and make a profit it might be unsustainable.

If they close shop, will they give us a warning and let us move over our sites to 20i or one of their resellers ?

I give it 4 tacos for the moment