As far as I know, the only people unlocking phones are Rogers. And they are unlocking their phones.
There are sooo many posts about unlocks. It's not possible now. It seems that options for unlocked phones are either buy it factory unlocked or buy it from rogers and have it unlocked.
I've had three 920's from Rogers. Two of them could not be unlocked by any company out there (only could be unlocked by paying $50 to Rogers), while the third (a replacement from Nokia directly) could be unlocked by cellunlocker.net. As far as I know, they are the only ones who have managed to unlock a subset of the Rogers Lumia 920. Note that the first two phones were from the 45/2012 and 47/2012 batches, while the one unlocked by cellunlocker was from the 44/2012 batch.
I just tried cellunlocker.net on my Lumia 920, 47/2012 version, locked to Rogers. When I checked the website with my IMEI they claimed that the code was in their database and is unlockable, so I went ahead and ordered it. A few hours later I was informed through email that they could not unlock it and refunded my fee.
Maybe they get commission or something for getting people to try it out... doesnt make sense if they know they cant...
I did read an article today at least in the UK, all the other Carriers will be selling the 920 starting January 2013..... So maybe at least the international version of the 920 will be unlockable by that time.
I haven't heard about the unlocking source you are specifying about. but i unlocked my Fiancee's Nokia Lumia 920 from SimpleUnlocking.Com . This site provided accurate unlock code at affordable cost. This site seems to be a legit one in unlocking services.