Wouldn’t recommend using the 680 at all to cut metal. Makita will void the warranty if found out it was used to cut metal, that’s if you had a warranty problem I guess. From memory a 165mm metal cutting blade is 5000 and the 680 is 5000, that’s push the blade at its limit. It will dull quickly. If I’m cutting steel on the 551 with the saw 45° to me I can feel chips hitting, it would be worst with the 680 because it doesn’t have that clear PC cover. The 553 is a lot better with the chip collection. FYI the 680 and 533 both have a 20mm arbor, will be the same in most metric countries. The North America 680 as a 5/8 arbor and their 533 has a 20mm arbor