I think it depends on speakers ... I have had Quad Kef, Falcon LS3, PMC and now Tannoy.
The biggest difference is the Tannoy speakers where it was immediately clear almost like jumping up a model. On the rest it has been marginal and sometimes pretending to yourself it made a huge difference.
So borrow some wire - try and then decide.
Out of interest my Harbeths had one terminal as it is something the designer thought worked and there was definitely a fashion for biwire speakers at one point that wasnt always sonically warranted except buyers demanded it and manufacturers supplied ....
The biggest difference is the Tannoy speakers where it was immediately clear almost like jumping up a model. On the rest it has been marginal and sometimes pretending to yourself it made a huge difference.
So borrow some wire - try and then decide.
Out of interest my Harbeths had one terminal as it is something the designer thought worked and there was definitely a fashion for biwire speakers at one point that wasnt always sonically warranted except buyers demanded it and manufacturers supplied ....