Before 5.1 My H25 would not work on XP Pro, now it does. But, it is twice the time for me to see the image on 5.1 vs 3.7, so I switch back to 3.7 for shooting. P25 works no prob on either. On the Win 7 64bit the H25 does connect. (If I remember correctly). if you need me to run this test, let me know. ..send PM.
5.1 I find strong in processing, not much advantage capturing, in fact it is rather sluggish. When you are used to almost instant view of the file capture of 3.7, it is hard to wait 2 to 3 seconds for the file to show up on 5.1
It took more days than I thought before Phase neede a full system read out for them to get into the issue, so I just switched back to 3.7.(in the middle of a shoot week).
They are both Phase, and both have their advantage. I couldn't be effecient with only one of them, but I would rely more so on 3.7 still :-)