Yup, I asked earlier, and I just tried myself. I can confirm it works without registering UDID. Don't waste your money it's a scam!
Looks like GSM don't need UDID activation but CDMA do, that is what i've made from this, if people are prepared to take that risk then good on them, but I don't want to be responsible for people with phones stuck on the activation page
My iPhone 5 that's CDMA needed activation and Jeremy's CDMA iPhone 4 needed it, you can go and confirm this with him if you want. As a content manager is doing an activation service, I can almost guarantee it's not a scam.