I had 605 on mine today for 3+ and pushed out 10 but fuck that was mad heavy son... I see dudes on YT pushing like 1000 pounds and they aren't like giant beasts and I couldn't even begin to imagine being under that load...
I don't really use the leg press machine except for maybe some calf raises but I've seen some sleds that weighed a lot more than others by at least 100 pounds or so. I noticed that I had to use a lot less weight to get the same effect.