Has anyone here used this lens? I am looking to get another lens for motorsports shooting and my 70-200 works alright for shooting directly in front of me, but at the race track I shoot at the grandstands are all on straightaways and I'd like to get some good corner shots. I will hand-hold this lens most of the time, possibly have a monopod. Is this going to be too tough to hand hold without IS? It'll mainly be daytime shots too, so I wouldn't miss the f/4 of the 300 IS USM, but it's the other lens I'd consider. Any suggestions? Thanks.