[DeTomaso] Porterfield vs stock pads?

[pantdino at aol.com]

Since I have rebuilt my rear calipers it seems like a logical time to consider changing pads too.  Yes, I know I should change the fronts too if I do that. 

I am familiar with the Porterfield R4S pads, which I had on my M3 for a while.  I took them off because they have poor cold (first stop in the morning or after 15 min of non-use) performance compared to OEM BMW pads.  However, I don't know how they compare to the stock Girling pads.

How do they compare to the stock Girling pads re rotor wear and braking force upon application when they are cold? 
I am aware of the fact that they have to be properly bedded in or they will squeal.

Who has the best price on Porterfields?  The company itself or a retailer?

Jim