Will I notice a big difference in flavor and performance with a good RDA or RBA over my dripping attys?
That depends on who you ask. Some of the RBA enthusiasts are diehard and almost evangelical in their insistence that rebuildables' flavor and performance is worlds better than anything else. They're convinced of that, happy about it, and can't be dissuaded.
I'm not in that camp. I use many of the available JDS (Juice Delivery Systems---atomizers, cartomizers, clearomizers, tanks, RDAs/RBAs). I drip into regular atomizers (510s, 306s, even 901s), but I also continue to use a couple cartos (mainly Kanger single-bottom-coil XL cartos), and numerous clearomizers (CE2s, CE4s, wire-mesh-wick CE5s). I also have 13 bottom-feeder mods, 12 of which are outfitted with rebuildables atties for which I build regular or micro-coils of varying gauges (27ga-32ga) that use silica, EkoWool, cotton, or hemp wicks. I even have a couple of Kayfun Lite/Russian 91 clones and a couple Genesis-style tank RBAs that use rolled wire mesh wicks, but I've not yet used any of those.
I've had to quit espousing the simple (and often simplistic) good/bad, better/worse comparative judgments.
Is atty-dripping really the purest form of tasting flavors? Are CE4s really "muted" in flavor delivery? Are RBAs with sub-ohm micro-coils really the greatest thing since sliced bread? I read those kinds of opinions often on ECF and have written some of them myself, but in actual fact I haven't found them to be consistently or universally true. My experience is that each JDS provides its own particular kind of vaping experience, which may overlap with others, but retains its relatively unique identity. They all work, and I appreciate each for what it does well, but none is flawless or without downsides.
Anyway, that's my story, and I'm sticking to it...