I'm starting to expand my shooting in the area of birds and have been quite successful with my 300 F4 and a borrowed 300 F2.8. My bodies are 7D and 1DMKIV. I'm looking to make a next big investment in longer glass and narrowed down my search to the above 2. Are there any experienced bird shooters out there who can provide me with some guidance? I think long term I may want both but for now (and for the peace in my marriage) I will only buy one.