Just heard back from Guillaume Stordeur, the man behind Lazy Nezumi Pro:
Thanks for bringing this up. Let me try to clear things up.
The occasional full-pressure line issue is a Photoshop bug (where they basically ignore tablet data for a stroke, no idea why), and can still happen with Lazy Nezumi. From my experience, this most often happens on the first stroke after alt-tabbing back from another window.
However, inconsistent pressure, or small spikes in pressure: that can be addressed with LN's pressure smoothing options.
Regards,
Guillaume