Hiya, the diode is a good laser to use and some here have had good results. Although, in my personal opinion, if you have dark hair and light skin (Skin type I II or a cross between II and III) the Alexanderlite lasers are very good. The GentleLase is one of the most recent models and very successful, if used on the correct hair and skin type. The whole concept with Alexanderlite lasers is that they target pigment, hence why light skin is great (as the laser won’t attack it) and dark hair (so the laser focuses in on that, the darker the hair the better).
In regards to the PPX laser, I have never heard of that. Maybe giving them an email and asking whether it is an IPL or a actual laser could yield some results. Although a safe bet is definatly the Alexanderlite or diode.
Hope this helps,
Benji