I've just bought a new bed. The old one had castors that had deformed very badly, even on a smooth tiled floor. As the old bed was going into a guest room I took one of the deformed castors to a builders yard to try to get another set of 4. The guy said "those are rated for 20 kg each".
Theres 200 kg of people on that bed every night (sadly, just the two of us), let alone a HDF super king sized base and an extra firm super king mattress and a large oak headboard! I estimate over 400 and maybe as much as 500 kgs all told, and the manufacturer (I had the bed made to order!) had put castors for 80 kg total
i'm another who feels that tall machinery on castors is a disaster in the making (I've shifted a lot of equipment in my working life, I have seen many scary things)
I would prefer the trolley jack system, where the machine is on a firm base untill the pallet truck is underneath and then back on the firm base as soon as poss.