Grey day

No, I don't know what this little thing is, but it was warbling very beautifully first thing.

To all you canon users out there: I am looking at investing (!) in a 70-300mm lens, currently for a 70D; ultimately for a full frame in the fullness of time... 

I have considered the latest consumer version or possibly 'L' glass if I can find a decent second hand one.  However, I am put off by the weight and relative chunkiness of the 'L' lens.  Does anyone out there have experience with either of these lenses?  Although the reviews of the consumer lens are somewhat mixed, they seem to suggest that there isn't a huge amount to pick between the two when it comes to image quality.  Any advice or insights would be hugely appreciated!