One thing we can do if we want to use vector is press forward with vector but then either render that out as linework or convert it to toonz raster. This will then 'seal' gaps that are created by vector stroke groupings because... raster and toonz raster doesn't have such a thing.
The idea would be to draw in vector and adjust as necessary... using the various tools unique to vector levels... and to get better resolution and fidelity of linework. Then transfer to toonz raster or raster for the purpose of leveraging features best suited for those level types.
And ultimately, I'll tend to draw in one and copy/paste into another so we might start with vector and copy/paste down to toonz raster or raster. We might also draw in toonz raster and copy/paste into a vector level.
Copy pasting from toonz raster to vector will automaically invoke the converter using the current settings of the convert dialogue so those settings might need to be tweaked to get opimal results.
When drawing with vector it can help to turn Snap on so that lines meet lines and gaps are avoided. Segment Erase is also a wonderful feature.