A generic "clean digital" filter sound that can do typical resonant sweeps would be acceptable for a web synth, and a purely additive emulation like that of IL Harmless would be good enough for almost everything. There's no such thing as a totally worthless sound, but some sounds are more immediately useful for musical purposes, and letting the filter break usually indicates a low attention to detail. Low-quality digital resonance tends to have a "dentist's drill" timbre to it, even when it's not broken.
A last thought: I don't know how your envelopes are made right now, but they matter a great deal to the timbre. The curvature matters, as does the speed. You can use a generic filter with poor resonance performance, but the overall result will still sound pretty good with quality oscillators and well-tuned envelopes.