A few notes:
1. The 70-200 seemed to have an easier time focusing and the images seemed to look better, even when using a tripod on both.
2. It seems that the 100–400 is so much more sensitive to blur, which makes sense because it is reaching twice as far when fully zoomed. I even used a 2 second timer on the 100-400 shot and it still looks a little blurry to me.
3. I don’t use the viewfinder when shooting the sun like this, I use live view. Looking at the sun through the viewfinder will blind you.
4. Both shots used a heavy grad filter to help even the exposure of the sun. I like to try to get that hard edge on the sun when I can, but without the help of some clouds, it can be a difficult to do using shutter speed alone as it makes the ocean look more black than anything. Cloud cover helps.
5. These images were taken on different days: