Well, as the official Windows Phone 7.5 Mango update is about to be officially released, the number of people who get their hands on the Mango builds seem to increase each day. In fact, the latest two handsets that have its Mango builds leaked would be for the HTC 7 Mozart and Samsung Omnia 7.
The Mozart leak is build 7720.68 according to the good people over at XDA, while and the Omnia 7 is an August build, being a minor update over previous versions. According to Mobiletechworld, this might “not be worth the effort (remember this is just an engineering firmware with the RTM OS code that we already have). The firmware version seems to be a tiny jump from the KC1 firmware (2424.11.3.1 vs 2424.11.8.2) and the Radio went from 2424.11.2.2 to 2424.11.7.2.”
I would say leave the leaked versions alone if you do not want to take the risk of bricking your hardware for the sake of curiosity.