I have both of these knives. To me, they are very different. The F1 and its sub four inch blade (3.8 in) is closer to the Bark River Gunny, available in both A2 and stainless steel, than the larger Bravo-1 available in A2 and CPM154 stainless. While 4.25 inches doesn't seem like much more than 3.8 on paper, its a big difference in these knives, mainly due to the Bravo-1's larger, wider blade. The Bravo-1 is my "go to" all around field knife. It will do just about everything you need and I don't have to worry too much about it, not that I worry about my F1 breaking. I don't baton and I don't abuse my knives. I like the handle size better on the Brravo-1 as I have large hands with long fingers. However, the F1 is also fine for me.
If you need stainless, got with the F1, or S1, as there price point is much less than the CPM154 Bravo-1. I now use my F1 as a back up knife which lives in my flight bag. I carry the Bravo-1 a lot. Either are very fine choices, and you should get both at some point. Everyone needs at least one F1.
Edit:
From a previous post of mine:
I have both the F1 and Bravo-1. (Actually have two Bravo-1's).
IMHO, they are very different knives. I like the stainless of the F1, and its a good, versatile woods/survival knife. Mine lives in my flight bag, but doesn't get used much, hence why I like the stainless. It is a SMALL, compact knife, with a 3.8 inch blade.
The Bravo-1 while only a bit longer is a much larger knife. Its thicker, with a wider, slightly longer blade at 4.25 inches. It feels much bigger than the F1 and gives me more all around confidence for the woods. I carry this knife on day hikes as well as backpacking/camping.
Hopefully somebody will post side by side pics. A better comparison to the F1 would be the ESEE-3, BRKT Gunny and Fiddleback Forge Production Recluse. I have these as well and its hard to pick from them. They are all that good.