Idle-wise it runs like a charm (I literally have never had discernible misfires or anything). Part throttle is really good, when I had good KMIFRL, KFMIOP, etc maps. Julex is also running this sensor and he contributed to the MAF stuff. His optimum MLHFM don't fit mine exactly, as we have different intake setups (you can see in the logs that my car starts to go lean at around 6000RPM).  I'm running the SDR big open element filter, and he is running a different filter inside of the stock airbox.  I plan to optimize KFKHFM, KFLF, FKKVS once I make the switch to the K-box, because that is ECU file that I'm eventually going to stick with forever (also I'm not really worried about it until K-box because it's not going crazy lean and I don't have egregious knock, bad EGT's or anything. You'll want all of the data points you can get. Because our MLHFM table is 512 values, you'll have to find the values in between. Maybe Julex can chime in with how much/where he changed MLHFM curve from the supplied values on the (if he changed them at all). 

Also, you don't need to pay for the transfer fn.  The bottom of this first link says that you can use the SCT-5000 calibration for the HPX (same sensor), and the  SCT-5000 data is posted in this second link:
http://www.vmptuning.com/store/index.php?p=product&id=193&parent=30
http://eectuning.org/forums/viewtopic.php?f=2&t=19762