p.2 #4 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
Lunchb0x8 wrote:
Well, the 70-300 is on its way.
Now just to wait and play the old game of, hopefully it ships soon and is a good copy!
Congratulations.... you will not regret it...... BTW, search around for people speaking of decent results with this lens and the Kenko 1.4 TC. I've not tried it, but hear good things.
p.2 #5 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
I'm very happy with the 100-400L, and don't need the speed (and weight) of the 70-200/2.8. I can add the 1.4X II and get even better reach, and still very good IQ.
Hopefully your 70-300 will make you happy in your shooting.
p.2 #9 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
Yea, I had played with the idea of many different lenses, and frankly, the 70-200 would have been nice, but not far enough. The 100-400 though, the push/pull zoom along with other issues brought up in reviews made me a little hesitant.
The 70-300 seems to be a great option, and worst case, if 3 months down the line, it works out to be absolute rubbish, I can sell it on for a minimal loss and get something else.
p.2 #10 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
John_T wrote:
...push/pull, natural and easy as pie. Think I've had mine eight years and never have understood anybody having a problem with it, other than some need to find fault with things or lacking adaptability.
However, it's very far from being weather-sealed. That means that the push-pull acts like a vacuum cleaner and, although it may not suck in a lot of dust, it certainly sucks in moisture and I've had a problem with internal condensation with my 100-400 on a couple of occasions. Nothing that a couple of hours in the airing cupboard didn't fix, but it meant I had to swap to my 2.8 and x2 to get 400mm (thankfully I had them with me in the car!)
Niall
p.2 #11 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
I've had two 100-400s and never had dust or moisture problems with either, though as I understand it, most zooms move air in and out when zooming and the more rapid the zooming and older the lens, the higher the possibility of dust or moisture getting in.
I had that moisture problem with a 70-300 DO in the Australian tropics, particularly, I think, due to in and out of the AC in cars and buildings. It dried out periodically without any consequences, but was an annoyance. I liked the 70-300 as a travel lens, mainly what it was designed for, but always had those moments of it coming up short at 300mm.
In my experience, there is always going to be something, too long, too short, to heavy, too big, AF, IS, et cetera ad infinitum, so you either buy everything or make well thought out or best guess choices based on what you want to do and where you are coming short and live with the little stuff.
p.2 #12 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
Lunchb0x8 wrote:
Well, the 70-300 is on its way.
Now just to wait and play the old game of, hopefully it ships soon and is a good copy!
I have this lens, which I use along with a 400mm DO (previously a 400mm 5.6L) for racetrack stuff. I think you'll like it. Small, light, and great IQ. For me it can double as a motorsports lens as well as a travel lens for vacations, where it and a 15-85mm is basically all I need for my 7D no matter where we go.
I had the 100-400mm before, and honestly I think you would have been fine either way. But since I found myself with a 400mm prime in my backpack no matter what (due to the ability to get 560mm with a 1.4TC when necessary), I decided the 70-300L made more sense for me.
p.2 #13 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
Lunchb0x8 wrote:
Yea, I had played with the idea of many different lenses, and frankly, the 70-200 would have been nice, but not far enough. The 100-400 though, the push/pull zoom along with other issues brought up in reviews made me a little hesitant.
The 70-300 seems to be a great option, and worst case, if 3 months down the line, it works out to be absolute rubbish, I can sell it on for a minimal loss and get something else.
I love the push/pull, and have in on another favorite lens: the 28-300L IS. Super fast focal length changes when hand held. Another great feature is being able to use the locking ring to lock a specific focal length.
I'm sure you won't find the 70-300L to be "total rubbish". I've yet to run into an "L" lens that wasn't very good, if not spectacular.
p.2 #14 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
get the 100-400. I had a TC with my old 70-200/2.8 non-IS, and the image quality just isn't as good. IMHO you are actually better off cropping than using the TC
p.2 #15 · What to get? 100-400L 4.5-5.6 or 70-200L 2.8 with 2X extender?
I have. Both the 70-200f2.8is and the 100-400. Get the 70-200 first. It is a much better lens even if it only has half the range. The f2.8 comes in handy and with a 1.4x becomes a f4 the 100-400 has trouble auto focusing with a 1.4x much less a 2.0x converter. I like the 100-400 but its not the 70-200 although they are about the same size and weight. I will not be parting with it as I find the extra range a bonus but could do the same with a 1.4 or 2.0 converter although I'm not a fan of the later one and rarely use the prior one now that I have the 100-400.
Read the thread and you will see that the OP got neither lens that he asked about:
That would not have been the lens I'd have chosen. 
I've yet to run into an "L" lens that wasn't very good, if not spectacular.