I’d like to upgrade my 300/4 lens to a 300/2.8. Originally, I picked the f4 over the f2.8 because of the closer focus (5ft vs. 8ft), lighter weight (2.6lb vs. 5.6lb) and much lower price. I discovered that I always use the 200/2.8 for close-range work and only use the 300 for ranges past 8ft anyway, and I would prefer a wider aperture.
Current B&H listing for the 300/4IS is $1379. I’m listing mine for $1179. It’s in excellent condition. The newest 300/2.8 is listing for $7200, but I can find a used older variant for closer to half that price.