Research will tell you this is an amazing lens; for me that's sufficient research but apparently not for you. Balancing an amazing lens vs. its cost (in weight, or gold, or other lenses abandoned) is really too subjective for me to delve into further. Maybe you should sell the two big ones, keep the 70-300 Di, and really lighten your load? I'd be amazed if that were the answer, but if your shoulder aches right now that sounds mighty nice, doesn't it?