This is what you would be up against with the adze. More work than the hand held band saw, but much less cost. It comes with a learning curve shaped similar to the result you are looking for. A new band saw goes for $5000.00ish. The adze I use cost $35.00, new, the axe was free.
This was the one of the larger rafters, most took half the time this one did. The video was not edited, it is real time.
An adze is a tool that can be used to slowly work up to your layout line. If you go slow and careful on the first one, you will probably get a good result. As you get better, your speed will pick up. You can also stop shy of the line and spokeshave the rest of the way.
I mentioned the spoke shave in the video. I am not a perfectionist, but I did use the spoke shave to clean up a few which were on the rough side, one or two only. I might of used it a bit more but it was dull and I had not taken the time to sharpen, it of late. The rafter used as a demo was one of the poorer examples but it gets the point across.
Try the adze on narrower stock first, say 3" stock and 2" or so deep on 4-6 inch stock. As practice just keep working the same piece as sacrifice. You need to train body mechanics for knowledge. By standing on blocks my feet and ankles are above the danger point, somewhat. The adze will create the curve, no need to lay out a curved line to follow. The line I had to hit was critical but the sweep leading to it varied a little. I measure with the adze on the top surface about the adze head length away from the stop then give it a little more which I work up to as the final, skewing the adze across the beam at that point. This can be seen in the vid.
I thought I remembered that Jack Sobon taught us to first start with an axe, then the adze to remove the axe marks, then a draw knife to remove the adze marks, then the spoke shave to remove the draw knife marks.... but you can adjust as needed....
Or, you can do the whole thing with a chisel bevel down and finish with the spokeshave, like I did on a project in January. But that was because I didn't have an adze handy.
for example- what could you do with a saw? check out the end details in Phleps- "The Craft of Log Building". though he would argue, old school, that design degenerated with the saw, still, i think a diamond is nice end treatment. though again, as per usual, you could do that also with an axe.