Hmm...

No, I haven't tried them.

About this 4 TMU's :
Actually, there are only 2 TMU's on the Voodoo5 5500 (there are no 'hidden' ones).

The idea behind this "4 TMU thingy" probably were Single-Texturing situations, where no Multitexturing is performed.
In such a case, half of the Texturing performance is indeed not used, as each TMU could render 2 in one pass.

But since all modern Games use Multitexturing for almost everything, nothing really to gain.
Also, getting the TMU's programmed to react dynamically on Single Textuing situations (to then render 4 Single Textures in one pass) is something that noone has realized yet (that I know of)...

Note that image quality in Drivers usually is dictated simply by their default settings (most modern 3rd Party mods have Alpha Blending set to Sharper and Video Filter Quality set to High as default, thus looking a bit better right from the get-go).

Greetings
FalconFly