It is mostly that way in the professional world– an open-back banjo just will not have the powerful, driving tone of a resonator banjo. That tone that hits you like the crack of a baseball and bat, like a train ripping through the crisp mountain air… the banjo sound that provides the driving force behind the music of Flatt & Scruggs, the New South, the Bluegrass Album Band, and a plethora of other bluegrass bands… THAT sound undeniably belongs to the resonator banjo.
Likewise, the calming, effortless-feeling sound of clawhammer and old time– the sound that doesn’t “hit” you at all, but rather cradles your ear in the manner of a peaceful mountain river or a light morning rain- is less often found in a resonator banjo.
FWIW, even some resonator banjos remind me a lot more of an old-time banjo. Certain brands or types of resonator banjos are a lot more mellow and less driving– a lot different than the classic Mastertone sound. A Nechville will sound quite different from a Huber, for instance. They are both incredible brands, but they are catering to different styles.
All that being said, play what YOU enjoy, especially if you’re not catering to an audience.
One thing that I’ve found, though, is that extra loudness and projection are not just for the stage and the jam. It is SO addictive to sit and try to just pull every last iota of tone out of a powerful flathead banjo!
If you have an interest/passion for old time, you’ll probably enjoy trying your hand at clawhammer/old time, too. It’s really fun and interesting! Personally, I don’t think it’s for me, because I don’t have a passion for that type of music (at least, not at this point)… so I am just left saying of old-time, “It’s really fun and interesting!”
Now, if you like that crisp flathead resonator sound but want a lightweight banjo, there is sort of a “best of both worlds”… some banjo makers build flathead resonator banjos without a full-weight tone ring, which significantly reduces the weight. Some banjos, like the style 1, have a brass hoop; others just have a wood rim. Check out this vid from Russ Carson:
One of those banjos has a full weight tone ring, one has a brass hoop, and one has only a wood rim. Yet, they are still up for the task of providing driving, crisp tone… especially in the hands of Russ!
So a lot of your decision depends on your motivation for upgrading– e.g. do you want a new banjo for a different style of music, different sound quality, etc., or is your main motivation better playability or just bragging rights? (not that any of us have ever felt that motivation)