Looking to get something with more reach than the 70-200mm lens. Does anyone have experience with any of these lenses on their C100 (or C300 / C500)? (Looking for any opinions, pros, cons, things to watch out for.)

Canon EF 70-300mm f/4-5.6L IS USM Lens 4426B002 B&H Photo Video

Canon EF 28-300mm f/3.5-5.6L IS USM Lens 9322A002 B&H Photo

Canon EF 100-400mm f/4.5-5.6L IS USM Lens 2577A002 B&H Photo

(or newly announced) Canon EF 100-400mm f/4.5-5.6L IS II USM Lens 9524B002 B&H Photo

Or should I just get a 1.4x or 2x extender?

Canon Extender EF 1.4X III 4409B002 B&H Photo Video

Canon Extender EF 2X III 4410B002 B&H Photo Video