The guy that used to do my setups had a '74 F-40, with the arched maple back, and I had the opportunity to play it at his shop on a number of occasions. I liked it alot... it had a very clean sound, with great note separation. I thought it would be great for finger style/picking. It wasn't the loudest... but had decent volume. In an A/B comparison, I found it to be sonically quite similar to my '74 G-37, a dread with arched maple back, tho' the G-37 had a bit more volume (tho' it was one of my quieter dreads at the time).
I also owned a '76 D-50 for some years... it was a loud (much louder than my maple G-37), in-your-face, rosewood dread. Lots of volume, very rich tone with lots of overtones, and gut rumbling bass. I really liked its sound... but it had a NARROW (closer to 1-5/8") but THICK neck that was uncomfortable to play for extended periods.
In a side-by-side, I preferred the '74 maple G-37 for finger picking, and the D-50 for strumming and flat-picking. Based on my experience with the '74 F-40... I'd expect to have the same preferences.
In the end... it all boils down to what your own style and sonic preferences are... Good luck!