When I was putting together my bottom end my machinist tried to get me with a set of those. I already had a set of Wiseco's and asked him what was so special about the Probes. He told me that they are basically the same as Wisecos (Forged) but that they would be a bit lighter.
If they are forged pistons, and my machinist wasn't BSing me to make a sale, then I would say go for it!
PS..
If those SpeedPros are the forged ones, they are heavier than hell! The Wisecos that I have are very light and have a perfectly flat top to them...the SpeedPros that I used to have (forged) were VERY lame in comparison. | 
