It's possibly next on my list for some reach beyond my RF 70-200 (the 600 STM was returned, I can see how it's good for some shooters but if I'm going that long, I'd like something which works in less abundant light servo situations)This 100-400 lens gets glowing reviews all round. Might have to rent it or just get it, it's quite the bargain and wasn't upped with the latest MAP increase.