Digital BW, The Print

I'm reading all I can on converting a printer to dedicated black and 
white.  Unfortunately, I'm not able to reach any conclusions on the 
suitability of one system over the other.

Can anyone give me a rundown of the competing systems and their 
advantages/disadvantages?

At the moment, I'm leaning toward the piezotone system because it 
seems straightforward and because the idea of doing split tones prints 
apeals to me.

I'm wishing I could get a hands-on look at output from the various 
systems, but I can't figure how to make that happen.