With clamp or with out it the unipivot tonearm stability will be there, you can't avoid it using any clamp type. The second pivot is not the total cure, it's only something to reduce the stability problems. Best is to look for pivot tonearm with fixed bearing design because the cartridge needs full proof stability: zero tolerance.
Unipivots are more easy to design but is not a tool to use for a cartridge ridding LP grooves. Is a mistake to use it that goes against the quality level performance. I know that some audiophiles really likes it but ( even that they don't know. ) it does not means is rigth.
We have remember to " see " the stability subject at the microscopic level that is where the cartridge stylus tip has to " negociates " those " rude " LP grooves. Believe me that the cartridge tracking job is a really hard and huge task and not so simple as we can imagine it.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.