Oh… you have no idea. There is a build you can do on siptah that allows you to transfer with like 10x more weight than you normally could thanks to the drowned sigil (Your encumberance goes up as your HP goes down). People were transferring with around 30 thralls worth of weight, which is about 3x more than a normal player min/maxing encumbrance can do.

The only downside is you lose all sigils upon transferring, but you just bring more.