I can see that upgrade. The biggest issue with the 50 f/1.8 is the AF. So, hopefully, the STM is a significant improvement. I was able to sell my 50 f/1.8 for $80. If you can do the same or similar you are looking at a $45 upgrade cost. I upgraded to the EF 50 f/1.4 which I thought was well worth it for the better AF and I thought better IQ at f/2.
We digress....it happens....
.....as we talked about on our drive, there are lots of ways to build a kit. At last at one point, Ben Taylor was using a kit of Rokinon 14 mm, 35L, 70-200 II. Wide range is covered with good glass, very straightforward. In a way, I absolutely love that set up.
Your basic kit, 16-35 f/4, 24A, 50A, 70-200, and Tamron 150-600. An even wider range covered.
And then you can add more and more lenses, but the niche for each lens becomes smaller and smaller. That may be where I am getting too. I want to cover many niches, but I do not want them so small that they do not get used.
The 24-70 II may at least make the 35A redundant. Maybe the 50A as well. That will be part of my tests. But something Rick (HDNitehawk) said when I was considering buying the 24-70II has stuck in the back of my head. Something to the extent that the 24-70II is "almost" as good as a prime. The example he gave was that many of other peoples favorite photos that he took where taken with the 24-70II where great IQ and the flexibility of the zoom allowed capturing different moments very well. But most of his favorite photos where taken with a prime.
I might be seeing that same thing develop. For awhile I had been shooting family events with the 24-70II. But recently I've mixed in the 50A and at least twice now my favorite shots were taken with the 50A. What I am learning is to not only use it where I can't use the 24-70II (wider than f/2.8), but also use it at overlapping apertures and it is just a bit sharper. And, just to circle back to the start of this digression, that is what I was seeing in David's shots. Several of them really have a specific "pop" to them that may be prime (as well as photographic skills )