Have you compared the 70-200 + 1.4x TC against the 70-300. With the TC, I no longer find a use for the 70-300.
The 70-300 IS USM is a great lens. Is it an "L" lens? No, but it doesn't have to be. I have done sharpness comparisons between the 70-200 f4L and the 70-300 IS USM at 200mm and they are both amazing. The 300 loses a little detail but it is worth it for the extra reach. I will never sell mine. I still use it and will continue to do so. It is worth every penny spent. It's a great lens in the EF line-up.
Too many people out there think that unless the lens is white or comes with a "red stripe" it is not worth owning. I do not believe that. Canon has several non-"L" lenses out there that are fantastic and some are even EF-s, the HORROR!!!
Do yourself a favor, get some 1/16' tomato red 3m stripe and put a band over the gold stripe at the end of the lens. That way no one will complain or even care to comment...
Hmmm, why not just dump the 200 and go for the 400L prime or 600L prime? The 1.4 tele works best on the 70-200 2.8L as the 4L can loose some AF speed in darker shooting areas. You are now looking at almost 3 grand for that setup or about $2600.00 for the 70-300 f4L setup. The 70-300 IS USM is $650.00. It is a VERY affordable lens that delivers excellent quality for a third the price.
Not everyone can afford "L" lenses nor should they be pressured into thinking that the equipment that they can afford "sucks" because it is not the "best of the best". Each camera body and each lens serves a purpose and they do the job for which they were designed.
This thread was "show your love for the 70-300", not "Hey, this lens sucks, what would you use instead?" Let's get back to the original post.